Error codes

`accessibility-unknown-keystroke-info-category`

Cannot add keystrokes in an unknown category. Use addKeystrokeInfoCategory to add a new category or make sure the specified category exists.

Parameters

categoryId : any: The id of the unknown keystroke category.
keystrokes : any: Keystroke definitions about to be added.

`accessibility-unknown-keystroke-info-group`

Cannot add keystrokes to an unknown group.

Use addKeystrokeInfoGroup to add a new group or make sure the specified group exists.

Parameters

groupId : any: The id of the unknown keystroke group.
categoryId : any: The id of category the unknown group should belong to.
keystrokes : any: Keystroke definitions about to be added.

`ai-commands-config-order-collision`

The same order value has been set for two (or more) definitions in the AI Assistant feature configuration.

Learn more about command definitions and group definitions used in the feature configuration

Parameters

conflictingDefinitions : any: Definitions that have the same order value.

`ai-invalid-license-key`

Invalid license key. Please contact our customer support at https://ckeditor.com/contact/.

`ai-trial-license-key-reached-limit-changes`

You have exhausted the trial usage limit (reason: reached document changes limit). Restart the editor.

Please contact our customer support to get a full access at https://ckeditor.com/contact/.

`aiadapter-text-adapter-not-set`

AI text adapter plugin has not been added to the editor. Use one of the provided adapter plugins (e.g. OpenAITextAdapter if you connect to OpenAI or Azure OpenAI service) or create a custom adapter.

`aitextadapter-send-request-failed`

Sending a request to the AI service API failed.

`alignment-config-classname-already-defined`

The same className in one of the alignment.options was already declared.

Parameters

option : any: First option that declares given className.
configuredOptions : any: Contents of alignment.options.

`alignment-config-classnames-are-missing`

The className property has to be defined for all options once at least one option declares className.

Parameters

configuredOptions : any: Contents of alignment.options.

`alignment-config-name-already-defined`

The same name in one of the alignment.options was already declared. Each name representing one alignment option can be set exactly once.

Parameters

option : any: First option that declares given name.
configuredOptions : any: Contents of alignment.options.

`alignment-config-name-not-recognized`

The name in one of the alignment.options is not recognized. The available options are: 'left', 'right', 'center' and 'justify'.

Parameters

option : any: Options with unknown value of the name property.

`annotation-invalid-target`

An error thrown when the target type is invalid.

The target should be either:

a DOM element or an array of DOM elements,
or a rect instance,
or null,
or a callback that returns one of the above.

`annotationcollection-duplicated-item`

The annotation already exists in the collection. It can not be added more than once.

`annotationcollection-not-existing-item`

The annotation does not exist in the collection and cannot be removed.

`annotationsuis-annotation-mismatch`

An annotation should always belong only to one annotations UI instance. Check filters that were passed to activate methods.

`annotationsuis-missing-ui`

UI with a given name has been not registered.

`annotationsuis-missing-ui`

UI with a given name has been not registered.

`annotationsuis-missing-ui`

UI with a given name has been not registered.

`annotationsuis-register-already-registered`

UI with a given name already registered.

`annotationsuis-register-invalid-interface`

The annotations UI plugin should implement AnnotationsUI interface.

`attachtoform-missing-elementapi-interface`

The editor passed to attachToForm() must implement the ElementApi interface.

`attribute-element-get-elements-with-same-id-no-id`

Cannot get elements with the same id for an attribute element without id.

`attribute-operation-attribute-exists`

The attribute with given key already exists for the given node.

`attribute-operation-range-not-flat`

The range to change is not flat.

`attribute-operation-wrong-old-value`

Changed node has different attribute value than operation's old attribute value.

`batch-constructor-deprecated-string-type`

The string value for a type property of the Batch constructor has been deprecated and will be removed in the near future. Please refer to the Batch constructor API documentation for more information.

`batch-type-deprecated`

The Batch#type property has been deprecated and will be removed in the near future. Use Batch#isLocal, Batch#isUndoable, Batch#isUndo and Batch#isTyping instead.

`cannot-change-view-tree`

Thrown when there is an attempt to make changes to the view tree when it is in incorrect state. This may cause some unexpected behaviour and inconsistency between the DOM and the view. This may be caused by:

calling change or forceRender during rendering process,
calling change or forceRender inside of post-fixer function.

`ckbox-access-default-workspace-error`

The user is not authorized to access the workspace defined in theckbox.defaultUploadWorkspaceId configuration.

`ckbox-fetch-category-http-error`

Fetching a list of available categories with which an uploaded file can be associated failed.

`ckbox-image-not-processed`

Image has not been processed yet.

`ckbox-image-processing-failed`

The image processing failed.

`ckbox-plugin-image-feature-missing`

The CKBox feature requires one of the following plugins to be loaded to work correctly:

ImageBlock,
ImageInline,
Image (loads both ImageBlock and ImageInline)

Please make sure your editor configuration is correct.

`ckbox-plugin-missing-token-url`

The config.ckbox.tokenUrl or the config.cloudServices.tokenUrl configuration is required for the CKBox plugin.

ClassicEditor.create( document.createElement( 'div' ), {
	ckbox: {
		tokenUrl: "YOUR_TOKEN_URL"
		// ...
	}
	// ...
} );

`ckeditor-duplicated-modules`

This error is thrown when due to a mistake in how CKEditor 5 was installed or initialized, some of its modules were duplicated (evaluated and executed twice). Module duplication leads to inevitable runtime errors.

There are many situations in which some modules can be loaded twice. In the worst case scenario, you may need to check your project for each of these issues and fix them all.

Trying to add a plugin to an existing build

If you import an existing CKEditor 5 build and a plugin like this:

import ClassicEditor from '@ckeditor/ckeditor5-build-classic';
import Highlight from '@ckeditor/ckeditor5-highlight/src/highlight';

Then your project loads some CKEditor 5 packages twice. How does it happen?

The build package contains a file which is already compiled with webpack. This means that it contains all the necessary code from e.g. @ckeditor/ckeditor5-engine and @ckeditor/ckeditor5-utils.

However, the Highlight plugin imports some of the modules from these packages, too. If you ask webpack to build such a project, you will end up with the modules being included (and run) twice – first, because they are included inside the build package, and second, because they are required by the Highlight plugin.

Therefore, you must never add plugins to an existing build unless your plugin has no dependencies.

Adding plugins to a build is done by taking the source version of this build (so, before it was built with webpack) and adding plugins there. In this situation, webpack will know that it only needs to load each plugin once.

Read more in the Installing plugins guide.

Confused an editor build with an editor implementation

This scenario is very similar to the previous one, but has a different origin.

Let's assume that you wanted to use CKEditor 5 from source, as explained in the "Building from source" section or in the "Quick start" guide of CKEditor 5 Framework.

The correct way to do so is to import an editor and plugins and run them together like this:

import ClassicEditor from '@ckeditor/ckeditor5-editor-classic/src/classiceditor';
import Essentials from '@ckeditor/ckeditor5-essentials/src/essentials';
import Paragraph from '@ckeditor/ckeditor5-paragraph/src/paragraph';
import Bold from '@ckeditor/ckeditor5-basic-styles/src/bold';
import Italic from '@ckeditor/ckeditor5-basic-styles/src/italic';

ClassicEditor
	.create( document.querySelector( '#editor' ), {
		plugins: [ Essentials, Paragraph, Bold, Italic ],
		toolbar: [ 'bold', 'italic' ]
	} )
	.then( editor => {
		console.log( 'Editor was initialized', editor );
	} )
	.catch( error => {
		console.error( error.stack );
	} );

However, you might have mistakenly imported a build instead of the source ClassicEditor. In this case your imports will look like this:

import ClassicEditor from '@ckeditor/ckeditor5-build-classic';
import Essentials from '@ckeditor/ckeditor5-essentials/src/essentials';
import Paragraph from '@ckeditor/ckeditor5-paragraph/src/paragraph';
import Bold from '@ckeditor/ckeditor5-basic-styles/src/bold';
import Italic from '@ckeditor/ckeditor5-basic-styles/src/italic';

This creates the same situation as in the previous section because you use a build together with source plugins.

Remember: @ckeditor/ckeditor5-build-* packages contain editor builds and @ckeditor/ckeditor5-editor-* contain source editors.

Loading two or more builds on one page

If you use CKEditor 5 builds, you might have loaded two (or more) ckeditor.js files on one web page. Check your web page for duplicated <script> elements or make sure your page builder/bundler includes CKEditor only once.

If you want to use two different types of editors at once, see the "Using two different editors" section.

Using outdated packages

Building CKEditor 5 from source requires using multiple npm packages. These packages have their dependencies to other packages. If you use the latest version of, for example, @ckeditor/ckeditor5-editor-classic with an outdated version of @ckeditor/ckeditor5-image, npm or yarn will need to install two different versions of @ckeditor/ckeditor5-core because @ckeditor/ckeditor5-editor-classic and @ckeditor/ckeditor5-image may require different versions of the core package.

The solution to this issue is to update all packages to their latest version. We recommend using tools like npm-check-updates which simplify this process.

Conflicting version of dependencies

This is a special case of the previous scenario. If you use CKEditor 5 with some third-party plugins, it may happen that even if you use the latest versions of the official packages and the latest version of these third-party packages, there will be a conflict between some of their dependencies.

Such a problem can be resolved by either downgrading CKEditor 5 packages (which we do not recommend) or asking the author of the third-party package to upgrade its depdendencies (or forking their project and doing this yourself).

Note: All official CKEditor 5 packages (excluding integrations and ckeditor5-dev-* packages) are released in the same major version. This means that in the x.y.z version, the x is the same for all packages. This is the simplest way to check whether you use packages coming from the same CKEditor 5 version. You can read more about versioning in the Versioning policy guide.

Packages were duplicated in `node_modules`

In some situations, especially when calling npm install multiple times, it may happen that npm will not correctly "deduplicate" packages.

Normally, npm deduplicates all packages so, for example, @ckeditor/ckeditor5-core is installed only once in node_modules/. However, it is known to fail to do so from time to time.

We recommend checking if any of the steps listed below help:

rm -rf node_modules && npm install to make sure you have a clean node_modules/ directory. This step is known to help in most cases.
If you use yarn.lock or package-lock.json, remove it before npm install.
Check whether all CKEditor 5 packages are up to date and reinstall them if you changed anything (rm -rf node_modules && npm install).

If all packages are correct and compatible with each other, the steps above are known to help. If not, you may try to check with npm ls how many times packages like @ckeditor/ckeditor5-core, @ckeditor/ckeditor5-engine and @ckeditor/ckeditor5-utils are installed. If more than once, verify which package causes that.

`ckfinder-missing-image-plugin`

CKFinder requires at least one plugin providing support for images loaded in the editor. Please make sure either:

Image (which loads both types of images),
or ImageBlock,
or ImageInline.

is loaded in your editor configuration.

`ckfinder-unknown-openermethod`

The ckfinder.openerMethod must be one of: "popup" or "modal".

`cloudservices-init`

An internal WebSocketGateway error.

This error might occur because of the incorrectly configured webSocketUrl * config.cloudServices.webSocketUrl} or because of the service handling the WebSocket connections being unavailable.

The original error is passed in the error.data.originalError property.

`cloudservices-reconnection-error`

An internal reconnection error.

`cloudservices-token-not-registered`

The provided tokenUrl was not registered by registerTokenUrl.

`cloudservicescommentsadapter-connect-already-connected`

Cannot connect to the same channelId more than once.

`cloudservicescommentsadapter-disconnect-not-exist`

Missing service with the given channelId.

`cloudservicescommentsadapter-service-not-exist`

Missing service of a given channelId.

`collaboration-missing-channelid`

Unique collaboration.channelId configuration is required for defining name for data stores. Note that application instances with the same channelId will share data each other.

`collection-add-invalid-id`

This item's ID should be a string.

`collection-add-item-already-exists`

This item already exists in the collection.

`collection-add-item-invalid-index`

The index passed to Collection#addMany() is invalid. It must be a number between 0 and the collection's length.

`collection-bind-to-rebind`

The collection cannot be bound more than once.

`collection-get-invalid-arg`

An index or ID must be given.

`collection-remove-404`

Item not found.

`commandcollection-command-not-found`

Command does not exist.

Parameters

commandName : any: Name of the command.

`commentsrepository-active-missing-comment-thread`

Cannot set a non-existent comment thread as an active. Check if comment thread of the given id is added to the repository.

`commentsrepository-active-not-attached`

Cannot set a not attached comment thread as an active. Comment thread has to be attached to the target element to set it as active.

`commentsrepository-adapter-already-set`

Cannot set adapter more than once.

`commentsrepository-add-comment-internal-error`

Adding comment threw an error.

`commentsrepository-add-comment-thread-internal-error`

Adding comment thread threw an error.

`commentsrepository-add-comment-to-missing-comment-thread`

Cannot add comment to a non-existent comment thread.

`commentsrepository-add-comment-user-not-exists`

Comment author is not defined in Users plugin.

`commentsrepository-attach-missing-comment-thread`

Cannot attach a non-existent comment thread.

`commentsrepository-duplicated-comment-thread-id`

Comment thread with a given id is already added to the repository.

`commentsrepository-fetch-comment-thread`

Fetching a comment thread failed.

`commentsrepository-get-comment-invalid-id`

Comment id has to be a string.

`commentsrepository-invalid-comment-authorid`

Comment author id has to be a string.

`commentsrepository-invalid-comment-content`

Comment content has to be a string.

`commentsrepository-invalid-comment-thread-id`

Comment thread id has to be a string.

`commentsrepository-invalid-commentid`

Comment id has to be a string.

`commentsrepository-missing-comment-thread`

Comment thread with a given id is not existing.

`commentsrepository-missing-target`

Target is required to open new comment thread.

`commentsrepository-missing-thread-and-adapter`

Comment thread with a given id is not added to the editor nor adapter is defined. See https://ckeditor.com/docs/ckeditor5/latest/features/collaboration/comments/comments-integration.html.

`commentsrepository-missing-thread-and-adapter-method`

Comment thread with a given id is not added to the editor nor adapter.getCommentThread() is defined. See https://ckeditor.com/docs/ckeditor5/latest/features/collaboration/comments/comments-integration.html.

`commentsrepository-remove-comment-internal-error`

Removing comment resulted in an error.

`commentsrepository-remove-comment-missing-comment-thread`

Cannot remove comment from a non-existent comment thread.

`commentsrepository-remove-comment-thread-internal-error`

Removing comment resulted in an error.

`commentsrepository-remove-missing-comment`

Cannot remove a non-existent Comment.

`commentsrepository-remove-missing-comment-thread`

Cannot remove a non-existent comment thread.

`commentsrepository-reopen-comment-thread`

Comment thread with a given id is not resolved.

`commentsrepository-reopen-comment-thread-internal-error`

Reopening comment thread resulted in an error.

`commentsrepository-resolve-comment-thread-internal-error`

Resolving comment thread resulted in an error.

`commentsrepository-resolved-comment-thread`

Comment thread with a given id has been already resolved.

`commentsrepository-update-comment-internal-error`

Updating comment resulted in an error.

`commentsrepository-update-comment-invalid-content`

Comment content has to be a string.

`commentsrepository-update-comment-missing-comment-thread`

Cannot update a comment of a non-existent comment thread.

`commentsrepository-update-comment-thread-internal-error`

Updating comment thread resulted in an error.

`commentsrepository-update-missing-comment`

Cannot update a non-existent Comment.

`componentfactory-item-missing`

The required component is not registered in the component factory. Please make sure the provided name is correct and the component has been correctly added to the factory.

Parameters

name : any: The name of the missing component.

`context-addeditor-private-context`

Cannot add multiple editors to the context which is created by the editor.

`context-initplugins-constructor-only`

Only a constructor function is allowed as a context plugin.

`context-initplugins-invalid-plugin`

Only a plugin marked as a context plugin is allowed to be used with a context.

`contextualballoon-add-view-exist`

Trying to add configuration of the same view more than once.

`contextualballoon-remove-view-not-exist`

Trying to remove the configuration of the view not defined in the stack.

`contextualballoon-showstack-stack-not-exist`

Trying to show a stack that does not exist.

`conversion-add-alias-dispatcher-not-registered`

Trying to register an alias for a dispatcher that nas not been registered.

`conversion-attribute-to-attribute-on-text`

This error occurs when a text node's attribute is to be downcasted by an Attribute to Attribute converter. In most cases it is caused by converters misconfiguration when only "generic" converter is defined:

editor.conversion.for( 'downcast' ).attributeToAttribute( {
	model: 'attribute-name',
	view: 'attribute-name'
} ) );

and given attribute is used on text node, for example:

model.change( writer => {
	writer.insertText( 'Foo', { 'attribute-name': 'bar' }, parent, 0 );
} );

In such cases, to convert the same attribute for both Element and Text nodes, text specific Attribute to Element converter with higher priority must also be defined:

editor.conversion.for( 'downcast' ).attributeToElement( {
	model: {
		key: 'attribute-name',
		name: '$text'
	},
	view: ( value, { writer } ) => {
		return writer.createAttributeElement( 'span', { 'attribute-name': value } );
	},
	converterPriority: 'high'
} ) );

`conversion-element-to-structure-disallowed-text`

This error occurs when a model element is downcasted via elementToStructure helper but the element was allowed to host $text by the model schema.

For instance, this may be the result of myElement allowing the content of $block in its schema definition:

// Element definition in schema.
schema.register( 'myElement', {
	allowContentOf: '$block',

	// ...
} );

// ...

// Conversion of myElement with the use of elementToStructure().
editor.conversion.for( 'downcast' ).elementToStructure( {
	model: 'myElement',
	view: ( modelElement, { writer } ) => {
		// ...
	}
} );

In such case, elementToElement() helper can be used instead to get around this problem:

editor.conversion.for( 'downcast' ).elementToElement( {
	model: 'myElement',
	view: ( modelElement, { writer } ) => {
		// ...
	}
} );

Parameters

elementName : any: The name of the element the structure is to be created for.

`conversion-for-unknown-group`

Trying to add a converter to an unknown dispatchers group.

`conversion-group-exists`

Trying to register a group name that has already been registered.

`conversion-model-consumable-not-consumed`

Some of the model items were not consumed while downcasting the model to view.

This might be the effect of:

A missing converter for some model elements. Make sure that you registered downcast converters for all model elements.
A custom converter that does not consume converted items. Make sure that you consumed all model elements that you converted from the model to the view.
A custom converter that called event.stop(). When providing a custom converter, keep in mind that you should not stop the event. If you stop it then the default converter at the lowest priority will not trigger the conversion of this node's attributes and child nodes.

Parameters

: any: :engine/model/item~Item>} items Items that were not consumed.

`conversion-slot-filter-incomplete`

Filters provided to writer.createSlot() are incomplete and exclude at least one children element (one of the children elements would not be assigned to any of the slots).

Parameters

element : any: The element of which children would not be properly allocated to multiple slots.

`conversion-slot-filter-overlap`

Filters provided to writer.createSlot() overlap (at least two filters accept the same child element).

Parameters

element : any: The element of which children would not be properly allocated to multiple slots.

`conversion-slot-mode-unknown`

Unknown slot mode was provided to writer.createSlot() in downcast converter.

`data-filter-invalid-definition`

The definition cannot be handled by the data filter.

Make sure that the registered definition is correct.

`datacontroller-get-detached-root`

Retrieving document data for a detached root.

This usually indicates an error as a detached root should be considered "removed" and should not be included in the document data.

`datacontroller-get-non-existent-root`

Cannot get data from a non-existing root. This error is thrown when DataController#get() method is called with a non-existent root name. For example, if there is an editor instance with only main root, calling get like:

data.get( { rootName: 'root2' } );

will throw this error.

`datacontroller-init-document-not-empty`

Cannot set initial data to a non-empty Document. Initial data should be set once, during the Editor initialization, when the version is equal 0.

`datacontroller-init-non-existent-root`

Cannot init data on a non-existent root. This error is thrown when DataController#init() method is called with non-existent root name. For example, if there is an editor instance with only main root, calling init like:

data.init( { main: '<p>Foo</p>', root2: '<p>Bar</p>' } );

will throw this error.

`datacontroller-set-non-existent-root`

Cannot set data on a non-existent root. This error is thrown when the DataController#set() method is called with non-existent root name. For example, if there is an editor instance with only the default main root, calling set like:

data.set( { main: '<p>Foo</p>', root2: '<p>Bar</p>' } );

will throw this error.

`detach-operation-on-document-node`

Cannot detach document node.

`document-outline-container-not-provided`

A DOM element to inject the document outline is not provided. Please set the config.documentOutline.container configuration option.

Parameters

editor : any: Editor instance related to error.

`document-outline-invalid-license-key`

Invalid license key. Please contact our customer support at https://ckeditor.com/contact/.

`document-outline-trial-license-key-reached-limit-changes`

You have exhausted the trial usage limit (reason: reached document changes limit). Restart the editor.

Please contact our customer support to get a full access at https://ckeditor.com/contact/.

`document-selection-gravity-wrong-restore`

Restoring gravity for an unknown UID is not possible. Make sure you are using a correct UID obtained from the overrideSelectionGravity to restore.

Parameters

uid : any: The unique identifier returned by _overrideGravity.

`document-selection-wrong-position`

Range from document selection starts or ends at incorrect position.

`domconverter-invalid-attribute-detected`

Invalid attribute name was ignored during rendering.

`domconverter-transparent-rendering-unsupported-in-editing-pipeline`

The dataPipeline:transparentRendering flag is supported only in the data pipeline.

`domconverter-unsafe-attribute-detected`

The DomConverter detected an interactive attribute in the editing pipeline. For the best editing experience, the attribute was renamed to data-ck-unsafe-attribute-[original attribute name].

If you are the author of the plugin that generated this attribute and you want it to be preserved in the editing pipeline, you can configure this when creating the element using DowncastWriter during the model–view conversion. Methods such as createContainerElement, createAttributeElement, or createEmptyElement accept an option that will disable filtering of specific attributes:

const paragraph = writer.createContainerElement( 'p',
	{
		class: 'clickable-paragraph',
		onclick: 'alert( "Paragraph clicked!" )'
	},
	{
		// Make sure the "onclick" attribute will pass through.
		renderUnsafeAttributes: [ 'onclick' ]
	}
);

Parameters

domElement : any: The DOM element the attribute was set on.
key : any: The original name of the attribute
value : any: The value of the original attribute

`domconverter-unsafe-script-element-detected`

While rendering the editor content, the DomConverter detected a <script> element that may disrupt the editing experience. To avoid this, the <script> element was replaced with <span data-ck-unsafe-element="script"></span>.

`domconverter-unsafe-style-element-detected`

While rendering the editor content, the DomConverter detected a <style> element that may affect the editing experience. To avoid this, the <style> element was replaced with <span data-ck-unsafe-element="style"></span>.

`easy-image-image-feature-missing`

The Easy Image feature requires one of the following plugins to be loaded to work correctly:

ImageBlock,
ImageInline,
Image (loads both ImageBlock and ImageInline)

Please make sure your editor configuration is correct.

`editingcontroller-reconvertmarker-marker-not-exist`

The marker with the provided name does not exist and cannot be reconverted.

Parameters

markerName : any: The name of the reconverted marker.

`editor-create-initial-data`

The config.initialData option cannot be used together with the initial data passed as the first parameter of Editor.create().

`editor-initial-data-replaced-with-revision-data`

The editor initial data and initial roots attributes were replaced with the most recent revision data, as the editor data was different from revision data.

This means that the editor data was either outdated (possible due to an error, e.g. the document data has not been saved after last changes during the previous editing session) or the data was post-processed after it was obtained from the editor.

Note, that changes in whitespaces are also considered a difference.

`editor-isreadonly-has-no-setter`

The Editor#isReadOnly property is read-only since version 34.0.0 and can be set only using Editor#enableReadOnlyMode( lockId ) and Editor#disableReadOnlyMode( lockId ).

Usage before version 34.0.0:

editor.isReadOnly = true;
editor.isReadOnly = false;

Usage since version 34.0.0:

editor.enableReadOnlyMode( 'my-feature-id' );
editor.disableReadOnlyMode( 'my-feature-id' );

`editor-missing-sourceelement`

Cannot update the source element of a detached editor.

The updateSourceElement() method cannot be called if you did not pass an element to Editor.create().

`editor-read-only-lock-id-invalid`

The lock ID is missing or it is not a string or symbol.

`editor-source-element-already-used`

A DOM element used to create the editor (e.g. InlineEditor.create()) has already been used to create another editor instance. Make sure each editor is created with an unique DOM element.

Parameters

element : any: DOM element that caused the collision.

`editor-ui-deprecated-editable-elements`

The EditorUI#_editableElements property has been deprecated and will be removed in the near future. Please use setEditableElement() and getEditableElement() methods instead.

Parameters

editorUI : any: Editor UI instance the deprecated property belongs to.

`editor-ui-deprecated-viewport-offset-config`

The EditorConfig#toolbar.viewportTopOffset property has been deprecated and will be removed in the near future. Please use EditorConfig#ui.viewportOffset instead.

`editor-wrong-element`

This error is thrown when trying to pass a <textarea> element to a create() function of an editor class.

The only editor type which can be initialized on <textarea> elements is the classic editor. This editor hides the passed element and inserts its own UI next to it. Other types of editors reuse the passed element as their root editable element and therefore <textarea> is not appropriate for them. Use a <div> or another text container instead:

<div id="editor">
	<p>Initial content.</p>
</div>

`editorannotations-invalid-source-callback`

Function required.

editorannotations-invalid-source-callback

`enableplaceholder-deprecated-text-option`

The "text" option in the enablePlaceholder() function is deprecated and will be removed soon.

See the Migration to v39 guide for more information on how to apply this change.

`error-saving-suggestion-data-suggestion-discarded`

An unexpected error happened when the suggestion data was being saved in the database. In order to avoid mismatch between document data and the suggestions database, the suggestion in the document has been automatically discarded.

`filerepository-no-upload-adapter`

You need to enable an upload adapter in order to be able to upload files.

This warning shows up when FileRepository is being used without defining an upload adapter.

If you see this warning when using one of the CKEditor 5 Builds it means that you did not configure any of the upload adapters available by default in those builds.

See the comprehensive "Image upload overview" to learn which upload adapters are available in the builds and how to configure them.

If you see this warning when using a custom build there is a chance that you enabled a feature like ImageUpload, or ImageUploadUI but you did not enable any upload adapter. You can choose one of the existing upload adapters listed in the "Image upload overview".

You can also implement your own image upload adapter.

`filerepository-read-wrong-status`

You cannot call read if the status is different than idle.

`filerepository-upload-wrong-status`

You cannot call upload if the status is different than idle.

`fileuploader-decoding-image-data-error`

Problem with decoding Base64 image data.

`fileuploader-missing-api-address`

Api address must be provided as the third argument.

`fileuploader-missing-file`

File must be provided as the first argument.

`fileuploader-missing-token`

Token must be provided as the second argument.

`fileuploader-uploading-data-failed`

Uploading file failed.

`focustracker-add-element-already-exist`

This element is already tracked by FocusTracker.

`font-size-invalid-definition`

Provided value as an option for FontSize seems to invalid.

See valid examples described in the plugin configuration.

`font-size-invalid-use-of-named-presets`

If config.fontSize.supportAllValues is true, you need to use numerical values as font size options.

See valid examples described in the plugin configuration.

Parameters

presets : any: Invalid values.

`html-embed-provide-sanitize-function`

When using the HTML embed feature with the htmlEmbed.showPreviews=true option, it is strongly recommended to define a sanitize function that will clean up the input HTML in order to avoid XSS vulnerability.

For a detailed overview, check the HTML embed feature documentation.

`image-block-plugin-required`

The ImageBlock plugin must be enabled to allow inserting block images. See type to learn more.

`image-inline-plugin-required`

The ImageInline plugin must be enabled to allow inserting inline images. See type to learn more.

`image-insert-integration-exists`

There are two insert-image integrations registered with the same name.

Make sure that you do not load multiple asset manager plugins.

`image-insert-integrations-not-registered`

The image insert feature requires integrations to be registered by separate features.

The insertImage toolbar button requires integrations to be registered by other features. For example ImageUpload, ImageInsert, ImageInsertViaUrl, CKBox

`image-insert-integrations-not-specified`

The insert image feature requires a list of integrations to be provided in the editor configuration.

The default list of integrations is upload, assetManager, url. Those integrations are included in the insert image dropdown if the given feature plugin is loaded. You should omit the integrations configuration key to use the default set or provide a selected list of integrations that should be used.

`image-insert-unknown-integration`

The specified insert image integration name is unknown or the providing plugin is not loaded in the editor.

`image-style-configuration-definition-invalid`

The image style definition provided in the configuration is invalid.

Please make sure the definition implements properly one of the following:

Parameters

dropdown : any: The name of the invalid drop-down
style : any: The name of the invalid image style option

`image-style-missing-dependency`

In order to work correctly, each image style option requires specific model elements (also: types of images) to be supported by the editor.

Model element names to which the image style option can be applied are defined in the modelElements property of the style option definition.

Explore the warning in the console to find out precisely which option is not supported and which editor plugins are missing. Make sure these plugins are loaded in your editor to get this image style option working.

Parameters

option : any: The name of the unsupported option.
missingPlugins : any: The names of the plugins one of which has to be loaded for the particular option.

`imageresizebuttons-missing-icon`

When configuring config.image.resizeOptions for standalone buttons, a valid icon token must be set for each option.

See all valid options described in the plugin configuration.

Parameters

option : any: Invalid image resize option.

`import-word-plugin-conversion-failed`

An error occurred while importing the Word file. Check the response from the Cloud Services in the browser's network tab in the developer tools to find out the reason.

`import-word-plugin-import-cancelled`

The import procedure has been cancelled. The position, where the content of the Word file should be inserted, no longer exists, because the document structure has changed. Choose the position again and try to import the Word file again.

`inlineannotations-attach-already-attached`

Cannot attach the same annotation twice.

`inlineannotations-detach-not-attached`

Cannot detach a UI if it is not attached.

`inlineannotations-not-allowed-with-context`

The InlineAnnotations plugin is not allowed as a Context plugin. It can be used as an editor plugin only.

`insert-operation-position-invalid`

Insertion position is invalid.

`insertcontent-invalid-insertion-position`

An internal error occurred when merging inserted content with its siblings. The insertion position should equal the merge position.

If you encountered this error, report it back to the CKEditor 5 team with as many details as possible regarding the content being inserted and the insertion position.

`insertcontent-wrong-position`

Given node cannot be inserted on the given position.

Parameters

node : any: Node to insert.
position : any: Position to insert the node at.

`insertobject-element-not-an-object`

Tried to insert an element with insertObject() function that is not defined as an object in schema. See SchemaItemDefinition. If you want to insert content that is not an object you might want to use insertContent() function.

`insertobject-invalid-place-parameter-value`

The unsupported options.setSelection parameter was passed to the insertObject() function. Check the insertObject() API documentation for allowed options.setSelection parameter values.

`invalid-date-time-format`

Date format must be a function.

`invalid-license-key`

Invalid license key. Please contact our customer support at https://ckeditor.com/contact/.

`keyboard-unknown-key`

Unknown key name. Only key names included in the keyCodes can be used.

`list-feature-conflict`

The List feature can not be loaded together with the LegacyList plugin.

Parameters

conflictPlugin : any: Name of the plugin.

`locale-deprecated-language-property`

The Locale#language property was deprecated and will be removed in the near future. Please use the Locale#uiLanguage and Locale#contentLanguage properties instead.

`mapping-model-position-view-parent-not-found`

A model position could not be mapped to the view because the parent of the model position does not have a mapped view element (might have not been converted yet or it has no converter).

Make sure that the model element is correctly converted to the view.

`marker-destroyed`

Cannot use a destroyed marker instance.

`markercollection-incorrect-marker-name`

Marker name cannot contain the "," character.

`markercollection-refresh-marker-not-exists`

Marker with provided name does not exists.

`matcher-pattern-deprecated-attributes-class-key`

The key-value matcher pattern for attributes option is using deprecated class key.

Use classes matcher pattern option instead:

// Instead of:
const pattern = {
	attributes: {
		key1: 'value1',
		key2: 'value2',
		class: 'foobar'
	}
}

// Use:
const pattern = {
	attributes: {
		key1: 'value1',
		key2: 'value2'
	},
	classes: 'foobar'
}

Refer to the Migration to v29.1.0 guide and the MatcherPattern documentation.

Parameters

pattern : any: Pattern with missing properties.

`matcher-pattern-deprecated-attributes-style-key`

The key-value matcher pattern for attributes option is using deprecated style key.

Use styles matcher pattern option instead:

// Instead of:
const pattern = {
	attributes: {
		key1: 'value1',
		key2: 'value2',
		style: /^border.*$/
	}
}

// Use:
const pattern = {
	attributes: {
		key1: 'value1',
		key2: 'value2'
	},
	styles: /^border.*$/
}

Refer to the Migration to v29.1.0 guide and MatcherPattern documentation.

Parameters

pattern : any: Pattern with missing properties.

`matcher-pattern-missing-key-or-value`

The key-value matcher pattern is missing key or value. Both must be present. Refer the documentation: MatcherPattern.

Parameters

pattern : any: Pattern with missing properties.

`media-embed-no-provider-name`

One of the providers (or extra providers) specified in the media embed configuration has no name and will not be used by the editor. In order to get this media provider working, double check your editor configuration.

`mention-feed-callback-error`

The callback used for obtaining mention autocomplete feed thrown and error and the mention UI was hidden or not displayed at all.

`mentioncommand-incorrect-id`

The feed item ID must start with the marker character.

Correct mention feed setting:

mentions: [
	{
		marker: '@',
		feed: [ '@Ann', '@Barney', ... ]
	}
]

Incorrect mention feed setting:

mentions: [
	{
		marker: '@',
		feed: [ 'Ann', 'Barney', ... ]
	}
]

See MentionConfig.

`mentioncommand-incorrect-marker`

The marker must be a single character.

Correct markers: '@', '#'.

Incorrect markers: '@@', '[@'.

See MentionConfig.

`mentionconfig-incorrect-marker`

The marker must be a single character.

Correct markers: '@', '#'.

Incorrect markers: '$$', '[@'.

See MentionConfig.

Parameters

marker : any: Configured marker

Adding unsupported components to the MenuBarView is not possible.

A component should be either a MenuBarMenuView (sub-menu) or a MenuBarMenuListItemButtonView (button).

Parameters

componentName : any: A name of the unsupported component used in the configuration.
componentView : any: An unsupported component view.

There was a problem processing the configuration of the menu bar. The item with the given name does could not be removed from the menu bar configuration.

This warning usually shows up when the Plugin which is supposed to provide a menu bar item has not been loaded or there is a typo in the menu bar configuration.

Parameters

menuBarConfig : any: The full configuration of the menu bar.
itemName : any: The name of the item that was not removed from the menu bar.

There was a problem processing the configuration of the menu bar. The configured item could not be added because the position it was supposed to be added to does not exist.

This warning usually shows up when the Plugin which is supposed to provide a menu bar item has not been loaded or there is a typo in the menu bar configuration.

Parameters

menuBarConfig : any: The full configuration of the menu bar.
itemName : any: The name of the item that was not removed from the menu bar.

There was a problem processing the configuration of the menu bar. The item with the given name does not exist so it was omitted when rendering the menu bar.

This warning usually shows up when the Plugin which is supposed to provide a menu bar item has not been loaded or there is a typo in the menu bar configuration.

Make sure the plugin responsible for this menu bar item is loaded and the menu bar configuration is correct, e.g. BoldUI is loaded for the 'menuBar:bold' menu bar item.

Parameters

menuBarConfig : any: The full configuration of the menu bar.
parentMenuConfig : any: The config of the menu the unavailable component was defined in.
componentName : any: The name of the unavailable component.

There was a problem processing the configuration of the menu bar. One of the menus is empty so it was omitted when rendering the menu bar.

This warning usually shows up when some plugins responsible for providing menu bar items have not been loaded and the menu bar configuration was not updated.

Make sure all necessary editor plugins are loaded and/or update the menu bar configuration to account for the missing menu items.

Parameters

menuBarConfig : any: The full configuration of the menu bar.
emptyMenuConfig : any: The definition of the menu that has no child items.

`merge-operation-how-many-invalid`

Merge operation specifies wrong number of nodes to move.

`merge-operation-source-position-invalid`

Merge source position is invalid. The element to be merged must have a parent node.

`merge-operation-target-position-invalid`

Merge target position is invalid. The element to be merged must have a parent node.

`model-createpositionat-offset-required`

Model#createPositionAt() requires the offset to be specified when the first parameter is a model item.

`model-document-createroot-name-exists`

A root with the specified name already exists.

`model-document-history-addoperation-incorrect-version`

Only operations with matching versions can be added to the history.

Parameters

errorData : any: The operation and the current document history version.

`model-liveposition-root-not-rootelement`

LivePosition's root has to be an instance of RootElement.

`model-node-not-found-in-parent`

The node's parent does not contain this node.

`model-nodelist-index-out-of-bounds`

Given index cannot be found in the node list.

`model-nodelist-insertnodes-not-node`

Trying to insert an object which is not a Node instance.

`model-nodelist-offset-out-of-bounds`

Given offset cannot be found in the node list.

Parameters

nodeList : any: Stringified node list.

`model-position-after-root`

You can not make a position after a root element.

`model-position-before-root`

You can not make a position before a root element.

`model-position-fromjson-no-root`

Cannot create position for document. Root with specified name does not exist.

`model-position-parent-incorrect`

Position parent have to be a model element or model document fragment.

`model-position-path-incorrect`

The position's path is incorrect. This means that a position does not point to a correct place in the tree and hence, some of its methods and getters cannot work correctly.

Note: Unlike DOM and view positions, in the model, the position's parent is always an element or a document fragment. The last offset in the position's path is the point in this element where this position points.

Read more about model positions and offsets in the Editing engine architecture guide.

Parameters

position : any: The incorrect position.

`model-position-path-incorrect-format`

Position path must be an array with at least one item.

`model-position-root-invalid`

Position root is invalid.

Positions can only be anchored in elements or document fragments.

`model-selection-range-intersects`

Trying to add a range that intersects with another range in the selection.

Parameters

addedRange : any: Range that was added to the selection.
intersectingRange : any: Range in the selection that intersects with addedRange.

`model-selection-set-ranges-not-range`

Selection range set to an object that is not an instance of Range.

Only Range instances can be used to set a selection. Common mistakes leading to this error are:

using DOM Range object,
incorrect CKEditor 5 installation with multiple ckeditor5-engine packages having different versions.

`model-selection-setfocus-no-ranges`

Cannot set selection focus if there are no ranges in selection.

`model-selection-setto-not-selectable`

Cannot set the selection to the given place.

Invalid parameters were specified when setting the selection. Common issues:

A TextProxy instance was passed instead of a real Text.
View nodes were passed instead of model nodes.
null/undefined was passed.

`model-selection-setto-required-second-parameter`

selection.setTo requires the second parameter when the first parameter is a node.

`model-textproxy-wrong-length`

Given length value is incorrect.

`model-textproxy-wrong-offsetintext`

Given offsetInText value is incorrect.

`model-tree-walker-no-start-position`

Neither boundaries nor starting position of a TreeWalker have been defined.

`model-tree-walker-unknown-direction`

Only backward and forward direction allowed.

`model-writer-insert-forbidden-move`

Cannot move a node from a document to a different tree. It is forbidden to move a node that was already in a document outside of it.

`move-operation-node-into-itself`

Trying to move a range of nodes into one of nodes from that range.

`move-operation-nodes-do-not-exist`

The nodes which should be moved do not exist.

`move-operation-range-into-itself`

Trying to move a range of nodes into the middle of that range.

`multi-root-editor-cannot-disable-graveyard-root`

You cannot disable the $graveyard root.

`multi-root-editor-load-root-already-loaded`

The root to load was already loaded before. The loadRoot() call has no effect.

`multi-root-editor-load-root-no-root`

The root to load does not exist.

`multi-root-editor-root-attributes-no-root`

Trying to set attributes on a non-existing root.

Roots specified in rootsAttributes do not match initial editor roots.

`multi-root-editor-root-initial-data-mismatch`

Editor roots do not match the initialData configuration.

This may happen for one of the two reasons:

Configuration error. The sourceElementsOrData parameter in MultiRootEditor.create() contains different roots than initialData configuration.
As the editor was initialized, the initialData configuration value or the state of the editor roots has been changed.

`narrowsidebar-attach-already-attached`

Cannot attach narrow sidebar twice.

`narrowsidebar-detach-not-attached`

Cannot detach not attached sidebar.

`observable-bind-duplicate-properties`

Properties must be unique.

`observable-bind-rebind`

Cannot bind the same property more than once.

`observable-bind-to-extra-callback`

Cannot bind multiple properties and use a callback in one binding.

`observable-bind-to-many-not-one-binding`

Binding one attribute to many observables only possible with one attribute.

`observable-bind-to-no-callback`

Binding multiple observables only possible with callback.

`observable-bind-to-parse-error`

Invalid argument syntax in to().

`observable-bind-to-properties-length`

The number of properties must match.

`observable-bind-wrong-properties`

All properties must be strings.

`observable-set-cannot-override`

Cannot override an existing property.

This error is thrown when trying to set a property with a name of an already existing property. For example:

let observable = new Model();
observable.property = 1;
observable.set( 'property', 2 );			// throws

observable.set( 'property', 1 );
observable.set( 'property', 2 );			// ok, because this is an existing property.

`observable-unbind-wrong-properties`

Properties must be strings.

`observablemixin-cannot-decorate-undefined`

Cannot decorate an undefined method.

Parameters

object : any: The object which method should be decorated.
methodName : any: Name of the method which does not exist.

`operation-utils-move-range-not-flat`

Trying to move a range which starts and ends in different element.

`operation-utils-remove-range-not-flat`

Trying to remove a range which starts and ends in different element.

`pagination-config-not-found`

The configuration required by the pagination plugin is missing. Follow the instructions provided in Pagination feature documentation to initialize the plugin properly.

Parameters

config : any: Configuration of the editor.

`pagination-invalid-license-key`

Invalid license key. Please contact our customer support at https://ckeditor.com/contact/.

`pagination-trial-license-key-reached-limit-changes`

You have exhausted the trial usage limit (reason: reached document changes limit). Restart the editor.

Please contact our customer support to get a full access at https://ckeditor.com/contact/.

`pendingactions-add-invalid-message`

The message must be a string.

`permissions-set-permissions-invalid-channel-id`

Trying to set permissions for a channelId that does not exist.

`plugin-obsolete-documentlist`

The DocumentList plugin is obsolete. Use List instead.

`plugin-obsolete-documentlistproperties`

The DocumentListProperties plugin is obsolete. Use ListProperties instead.

`plugin-obsolete-tododocumentlist`

The TodoDocumentList plugin is obsolete. Use TodoList instead.

`plugincollection-context-required`

If a plugin is a context plugin, all plugins it requires should also be context plugins instead of plugins. In other words, if one plugin can be used in the context, all its requirements should also be ready to be used in the context. Note that the context provides only a part of the API provided by the editor. If one plugin needs a full editor API, all plugins which require it are considered as plugins that need a full editor API.

Parameters

plugin : any: The name of the required plugin.
requiredBy : any: The name of the parent plugin.

`plugincollection-plugin-for-replacing-cannot-have-dependencies`

The plugin replacing an existing plugin cannot depend on other plugins.

`plugincollection-plugin-for-replacing-not-exist`

The replaced plugin does not exist in the available plugins collection.

`plugincollection-plugin-for-replacing-not-loaded`

The replaced plugin will not be loaded so it cannot be replaced.

`plugincollection-plugin-name-conflict`

Two plugins with the same pluginName were loaded. This will lead to runtime conflicts between these plugins.

In practice, this warning usually means that new plugins were added to an existing CKEditor 5 build. Plugins should always be added to a source version of the editor (@ckeditor/ckeditor5-editor-*), not to an editor imported from one of the @ckeditor/ckeditor5-build-* packages.

Check your import paths and the list of plugins passed to Editor.create() or specified in Editor.builtinPlugins.

The second option is that your node_modules/ directory contains duplicated versions of the same CKEditor 5 packages. Normally, on clean installations, npm deduplicates packages in node_modules/, so it may be enough to call rm -rf node_modules && npm i. However, if you installed conflicting versions of some packages, their dependencies may need to be installed in more than one version which may lead to this warning.

Technically speaking, this error occurs because after adding a plugin to an existing editor build the dependencies of this plugin are being duplicated. They are already built into that editor build and now get added for the second time as dependencies of the plugin you are installing.

Parameters

pluginName : any: The duplicated plugin name.
plugin1 : any: The first plugin constructor.
plugin2 : any: The second plugin constructor.

`plugincollection-plugin-not-found`

A plugin is not available and could not be loaded.

Plugin classes (constructors) need to be provided to the editor before they can be loaded by name. This is usually done in CKEditor 5 builds by setting the builtinPlugins property.

If you see this warning when using one of the CKEditor 5 Builds, it means that you try to enable a plugin which was not included in that build. This may be due to a typo in the plugin name or simply because that plugin is not a part of this build. In the latter scenario, read more about custom builds.

If you see this warning when using one of the editor creators directly (not a build), then it means that you tried loading plugins by name. However, unlike CKEditor 4, CKEditor 5 does not implement a "plugin loader". This means that CKEditor 5 does not know where to load the plugin modules from. Therefore, you need to provide each plugin through a reference (as a constructor function). Check out the examples in "Building from source".

Parameters

plugin : any: The name of the plugin which could not be loaded.

`plugincollection-plugin-not-loaded`

The plugin is not loaded and could not be obtained.

Plugin classes (constructors) need to be provided to the editor and must be loaded before they can be obtained from the plugin collection. This is usually done in CKEditor 5 builds by setting the builtinPlugins property.

Note: You can use editor.plugins.has() to check if a plugin was loaded.

Parameters

plugin : any: The name of the plugin which is not loaded.

`plugincollection-replace-plugin-invalid-type`

The plugin replacing an existing plugin must be a function.

`plugincollection-replace-plugin-missing-name`

The plugin replacing an existing plugin must have a name.

`plugincollection-replaced-plugin-cannot-have-dependencies`

The replaced plugin cannot depend on other plugins.

`plugincollection-required`

Cannot load a plugin because one of its dependencies is listed in the removePlugins option.

Parameters

plugin : any: The name of the required plugin.
requiredBy : any: The name of the parent plugin.

`plugincollection-soft-required`

A required "soft" dependency was not found on the plugin list.

When configuring the editor, either prior to building (via Editor.builtinPlugins) or when creating a new instance of the editor (e.g. via config.plugins), you need to provide some of the dependencies for other plugins that you used.

This error is thrown when one of these dependencies was not provided. The name of the missing plugin can be found in missingPlugin and the plugin that required it in requiredBy.

In order to resolve it, you need to import the missing plugin and add it to the current list of plugins (Editor.builtinPlugins or config.plugins/config.extraPlugins).

Soft requirements were introduced in version 26.0.0. If you happen to stumble upon this error when upgrading to version 26.0.0, read also the Migration to 26.0.0 guide.

Parameters

missingPlugin : any: The name of the required plugin.
requiredBy : any: The name of the plugin that requires the other plugin.

`presencelist-collapseat-invalid-format`

The config.presenceList.collapseAt configuration value must be a number greater than 0.

`presencelist-missing-container`

Missing container element for the presence list. Please make sure config.presenceList.container is set and refers to an existing DOM element.

`range-create-from-ranges-empty-array`

At least one range has to be passed to Range._createFromRanges().

`realtimecollaborationclient-editor-setdata-and-editor-data-set-are-forbidden-in-real-time-collaboration`

Trying to use editor.setData() or editor.data.set() in real-time collaboration. Re-setting data in real-time collaboration usually means a mistake (incorrect integration or plugin). Using it may overwrite local (not yet synchronized) changes on remote clients. If you tried to set editor initial data, use initialData configuration option instead. If you tried to set editor data in a plugin, consider applying the changes through the Writer in a model.change() block. If you understand effects of using editor.data.set() in real-time collaboration and want to suppress this error, set suppressErrorInCollaboration flag to true in the second parameter of editor.data.set() call: editor.data.set( '<p>Your data</p>', { suppressErrorInCollaboration: true } ).

`realtimecollaborationclient-handleserverresponse`

Server response error.

`realtimecollaborationclient-init-document-already-initialized`

Trying to set initial data to initialized document.

`realtimecollaborationclient-init-non-existent-root`

Attempting to init data on a non-existing root.

`realtimecollaborationclient-init-session-connection-error`

Connecting to the session resulted in an error.

`realtimecollaborationclient-initservice-internal-error`

Internal CollaborativeEditingService error.

`rename-operation-wrong-name`

Element to change has different name than operation's old name.

`rename-operation-wrong-position`

Given position is invalid or node after it is not instance of Element.

`revision-history-missing-configuration`

Configuration for revision history plugin is missing.

Please refer to documentation to learn how to set up the plugin.

`rootattribute-operation-attribute-exists`

The attribute with given key already exists for the given node.

`rootattribute-operation-fromjson-no-root`

Cannot create RootAttributeOperation for document. Root with specified name does not exist.

`rootattribute-operation-not-a-root`

The element to change is not a root element.

`rootattribute-operation-wrong-old-value`

The attribute which should be removed does not exist for the given node.

`schema-cannot-extend-missing-item`

Cannot extend an item which was not registered yet.

This error happens when a plugin tries to extend the schema definition of an item which was not registered yet.

Parameters

itemName : any: The name of the model element which is being extended.

`schema-cannot-register-item-twice`

A single item cannot be registered twice in the schema.

This situation may happen when:

Two or more plugins called register() with the same name. This will usually mean that there is a collision between plugins which try to use the same element in the model. Unfortunately, the only way to solve this is by modifying one of these plugins to use a unique model element name.
A single plugin was loaded twice. This happens when it is installed by npm/yarn in two versions and usually means one or more of the following issues:
- a version mismatch (two of your dependencies require two different versions of this plugin),
- incorrect imports (this plugin is somehow imported twice in a way which confuses webpack),
- mess in node_modules/ (rm -rf node_modules/ may help).

Note: Check the logged itemName to better understand which plugin was duplicated/conflicting.

Parameters

itemName : any: The name of the model element that is being registered twice.

`schema-check-merge-no-element-after`

The node after the merge position must be an element.

`schema-check-merge-no-element-before`

The node before the merge position must be an element.

`sessions-register-already-registered`

Sessions of given channelId already registered.

`sessions-unregister-not-exist`

Cannot unregister not registered sessions.

Missing container element.

Container element is not a HTMLElement.

`simple-upload-adapter-missing-uploadurl`

The config.simpleUpload.uploadUrl configuration required by the SimpleUploadAdapter is missing. Make sure the correct URL is specified for the image upload to work properly.

`slash-command-execute-missing`

Either execute or commandName has to be specified in SlashCommandDefinition.

`source-editing-incompatible-with-real-time-collaboration`

Source editing feature is not fully compatible with real-time collaboration, and using it may lead to data loss. Please read source editing feature guide to learn more.

If you understand the possible risk of data loss, you can enable the source editing by setting the allowCollaborationFeatures configuration flag to true.

`special-character-invalid-group-name`

The name "All" for a special category group cannot be used because it is a special category that displays all available special characters.

`special-character-invalid-order-group-name`

One of the special character groups in the "specialCharacters.order" configuration doesn't exist.

`split-operation-graveyard-position-invalid`

Graveyard position invalid.

`split-operation-how-many-invalid`

Split operation specifies wrong number of nodes to move.

`split-operation-position-invalid`

Split position is invalid.

`split-operation-split-in-root`

Cannot split root element.

`style-command-executed-with-incorrect-style-name`

Style command can be executed only with a correct style name.

This warning may be caused by:

passing a name that is not specified in the configuration (e.g. a CSS class name),
when trying to apply a style that is not allowed on a given element.

`tableslot-getter-removed`

This TableSlot's getter (property) was removed in CKEditor 5 v20.0.0.

Check out the new TableWalker's API in the documentation.

`tableutils-insertrows-insert-out-of-range`

The options.at points at a row position that does not exist.

`tableutils-removerows-row-index-out-of-range`

The options.at param must point at existing row and options.rows must not exceed the rows in the table.

`template-extend-render`

Extending a template after rendering may not work as expected. To make sure the extending works for an element, make sure it happens before render is called.

`token-cannot-download-new-token`

Cannot download new token from the provided url.

`token-missing-token-url`

A tokenUrl must be provided as the first constructor argument.

`token-not-in-jwt-format`

The provided token must follow the JSON Web Tokens format.

`toolbarview-item-unavailable`

There was a problem processing the configuration of the toolbar. The item with the given name does not exist so it was omitted when rendering the toolbar.

This warning usually shows up when the Plugin which is supposed to provide a toolbar item has not been loaded or there is a typo in the toolbar configuration.

Make sure the plugin responsible for this toolbar item is loaded and the toolbar configuration is correct, e.g. Bold is loaded for the 'bold' toolbar item.

You can use the following snippet to retrieve all available toolbar items:

Array.from( editor.ui.componentFactory.names() );

Parameters

item : any: The name of the component or nested toolbar definition.

`toolbarview-line-break-ignored-when-grouping-items`

The toolbar multiline breaks (- items) only work when the automatic button grouping is disabled in the toolbar configuration. To do this, set the shouldNotGroupWhenFull option to true in the editor configuration:

const config = {
	toolbar: {
		items: [ ... ],
		shouldNotGroupWhenFull: true
	}
}

Learn more about toolbar configuration.

A dropdown definition in the toolbar configuration is missing a text label.

Without a label, the dropdown becomes inaccessible to users relying on assistive technologies. Make sure the label property is set in your drop-down configuration:

 {
 	label: 'A human-readable label',
	icon: '...',
	items: [ ... ]
 },

Learn more about toolbar configuration.

`track-changes-accept-suggestion-not-found`

Suggestion to accept does not exist.

`track-changes-adapter-already-set`

Cannot set an adapter more than once.

`track-changes-adapter-missing-getsuggestion`

Adapter not set or is missing getSuggestion() method.

`track-changes-command-not-found`

Trying to enable command that does not exist.

`track-changes-data-invalid-editor-creator`

Editor creator has to be a function.

`track-changes-discard-suggestion-not-found`

Suggestion to discard does not exist.

`track-changes-enable-command-twice`

Trying to enable the same command twice.

`track-changes-suggestion-data-mismatch`

Suggestion marker data does not match loaded suggestion data.

`track-changes-suggestion-not-found`

Suggestion with given id not found.

`track-changes-user-not-found`

User with given id not found.

`translation-service-quantity-not-a-number`

An incorrect value was passed to the translation function. This was probably caused by an incorrect message interpolation of a plural form. Note that for messages supporting plural forms the second argument of the t() function should always be a number or an array with a number as the first element.

`trial-license-key-reached-limit-changes`

You have exhausted the trial usage limit (reason: reached document changes limit). Restart the editor.

Please contact our customer support to get a full access at https://ckeditor.com/contact/.

`trial-license-key-reached-limit-revisions`

You have exhausted the trial usage limit (reason: reached revisions number limit).

Please contact our customer support to get a full access at https://ckeditor.com/contact/.

`trial-license-key-reached-limit-time`

You have exhausted the trial usage limit (reason: reached time limit). Restart the editor.

Please contact our customer support to get a full access at https://ckeditor.com/contact/.

The child view of a dropdown is missing the focus() method and could not be focused when the dropdown got open.

Making the content of a dropdown focusable in this case greatly improves the accessibility. Please make the view instance implements the focusable interface for the best user experience.

The child view of a dropdown could not be focused because it is missing the focus() method.

This warning appears when a dropdown gets open and it attempts to focus the first child of its panel but the child does not implement the focusable interface.

Focusing the content of a dropdown on open greatly improves the accessibility. Please make sure the view instance provides the focus() method for the best user experience.

`ui-template-extend-children-mismatch`

The number of children in extended definition does not match.

`ui-template-revert-not-applied`

Attempting to revert a template which has not been applied yet.

`ui-template-wrong-syntax`

Node definition cannot have the "tag" and "text" properties at the same time. Node definition must have either "tag" or "text" when rendering a new Node.

`ui-textarea-view-min-rows-greater-than-max-rows`

The minimum number of rows is greater than the maximum number of rows.

Parameters

textareaView : any: The misconfigured textarea view instance.
minRows : any: The value of minRows property.
maxRows : any: The value of maxRows property.

`ui-view-render-already-rendered`

This View has already been rendered.

`ui-viewcollection-delegate-wrong-events`

All event names must be strings.

`unexpected-error`

An unexpected error occurred inside the CKEditor 5 codebase. This error will look like the original one to make the debugging easier.

This error is only useful when the editor is initialized using the Watchdog feature. In case of such error (or any CKEditorError error) the watchdog should restart the editor.

`uploadgateway-missing-api-address`

Api address must be provided.

`uploadgateway-missing-token`

Token must be provided.

`users-add-duplicated-id`

User with a given id is already added.

`users-add-invalid-id`

The id must be a string.

`users-me-already-defined`

Cannot add a local user more than once.

`users-me-missing-user`

Cannot specify a non-existing user as the local user.

`view-conversion-dispatcher-incorrect-result`

Incorrect conversion result was dropped.

Model range should be a conversion result.

`view-createpositionat-offset-required`

View#createPositionAt() requires the offset to be specified when the first parameter is a view item.

`view-emptyelement-cannot-add`

Cannot add children to EmptyElement.

`view-node-not-found-in-parent`

The node's parent does not contain this node. It means that the document tree is corrupted.

`view-position-after-root`

You can not make a position after a root.

`view-position-before-root`

You cannot make a position before a root.

`view-rawelement-cannot-add`

Cannot add children to a RawElement instance.

`view-renderer-filler-was-lost`

The inline filler node was lost. Most likely, something overwrote the filler text node in the DOM.

`view-renderer-unknown-type`

Unknown type passed to Renderer.markToSync.

`view-selection-add-range-not-range`

Selection range set to an object that is not an instance of Range.

`view-selection-range-intersects`

Trying to add a range that intersects with another range from selection.

Parameters

addedRange : any: Range that was added to the selection.
intersectingRange : any: Range from selection that intersects with addedRange.

`view-selection-setfocus-no-ranges`

Cannot set selection focus if there are no ranges in selection.

`view-selection-setto-not-selectable`

Cannot set selection to given place.

`view-selection-setto-required-second-parameter`

selection.setTo requires the second parameter when the first parameter is a node.

`view-textproxy-wrong-length`

Given length value is incorrect.

`view-textproxy-wrong-offsetintext`

Given offsetInText value is incorrect.

`view-tree-walker-no-start-position`

Neither boundaries nor starting position have been defined.

`view-tree-walker-unknown-direction`

Only backward and forward direction allowed.

`view-uielement-cannot-add`

Cannot add children to UIElement.

`view-writer-break-non-container-element`

Trying to break an element which is not a container element.

`view-writer-break-root`

Trying to break root element.

`view-writer-cannot-break-empty-element`

Cannot break an EmptyElement instance.

This error is thrown if DowncastWriter#breakAttributes() was executed in an incorrect position.

`view-writer-cannot-break-raw-element`

Cannot break a RawElement instance.

This error is thrown if DowncastWriter#breakAttributes() was executed in an incorrect position.

`view-writer-cannot-break-ui-element`

Cannot break a UIElement instance.

This error is thrown if DowncastWriter#breakAttributes() was executed in an incorrect position.

`view-writer-insert-invalid-node-type`

One of the nodes to be inserted is of an invalid type.

Nodes to be inserted with DowncastWriter#insert() should be of the following types:

`view-writer-invalid-create-slot-context`

The createSlot() method is only allowed inside the elementToStructure downcast helper callback.

`view-writer-invalid-position-container`

Position's parent container cannot be found.

`view-writer-invalid-range-container`

The container of the given range is invalid.

This may happen if range start and range end positions are not placed inside the same container element or a parent container for these positions cannot be found.

Methods like DowncastWriter#remove(), DowncastWriter#clean(), DowncastWriter#wrap(), DowncastWriter#unwrap() need to be called on a range that has its start and end positions located in the same container element. Both positions can be nested within other elements (e.g. an attribute element) but the closest container ancestor must be the same.

`view-writer-merge-containers-invalid-position`

Element before and after given position cannot be merged.

`view-writer-unwrap-invalid-attribute`

The attribute passed to DowncastWriter#unwrap() must be an instance of AttributeElement.

`view-writer-wrap-invalid-attribute`

The attribute passed to DowncastWriter#wrap() must be an instance of AttributeElement.

`viewconsumable-invalid-attribute`

Class and style attributes should be handled separately in ViewConsumable#add().

What you have done is trying to use:

consumables.add( { attributes: [ 'class', 'style' ] } );

While each class and style should be registered separately:

consumables.add( { classes: 'some-class', styles: 'font-weight' } );

`websocketgateway-invalid-plugin-interface`

Cannot add a plugin that does not implement the reconnect() method to the WebSocketGateway reconnection stack.

`websocketgateway-missing-token`

The authentication tokenUrl * config.cloudServices.tokenUrl} configuration is required for creating a websocket connection.

`websocketgateway-missing-websocket-url`

The config.cloudServices.webSocketUrl configuration is required for creating a websocket connection in the real-time collaboration.

ClassicEditor.create( document.createElement( 'div' ), {
	cloudServices: {
		webSocketUrl: "YOUR_WEBSOCKET_URL"
		// ...
	}
	// ...
} );

`websocketgateway-plugin-already-registered`

A plugin was added twice to the WebSocketGateway reconnection stack.

`widesidebar-attach-already-attached`

Cannot attach wide sidebar twice.

`widesidebar-detach-not-attached`

Cannot detach not attached sidebar.

The element passed to toWidget() must be a ContainerElement instance.

Parameters

element : any: The view element passed to toWidget().

Toolbar with the given id was already added.

Parameters

toolbarId : any: Toolbar id.

When registering a new widget toolbar, you need to provide a non-empty array with the items that will be inserted into the toolbar.

If you see this error when integrating the editor, you likely forgot to configure one of the widget toolbars.

See for instance:

Parameters

toolbarId : any: The id of the toolbar that has not been configured correctly.

Parameters

markerName : any: The name of the updated marker.

Parameters

Parameters

Parameters

Parameters

Parameters

Parameters

Parameters

Trying to add a plugin to an existing build

Confused an editor build with an editor implementation

Loading two or more builds on one page

Using outdated packages

Conflicting version of dependencies

Packages were duplicated in node_modules

Parameters

Parameters

Parameters

Parameters

Parameters

Parameters

Parameters

Parameters

Parameters

Parameters

Parameters

Packages were duplicated in `node_modules`