id,summary,reporter,owner,description,type,status,priority,milestone,component,version,resolution,keywords,cc 13410,"[Embedbase, autoembed] Error thrown when undo action follows widget.loadContent",Olek Nowodziński,Szymon Kupś,"1. Go to http://tests.ckeditor.dev:1030/tests/plugins/autoembed/manual/autoembed. 2. Copy an embed link. 3. Paste it. 4. CTRL+Z immediately, before it embeds. **Expected**: Embedding is aborted. **Actual**: `TypeError: Cannot set property 'ready' of null` error is thrown **The reason**: `autoEmbedLink()` function calls `loadContent()` on a temporary widget instance (located in docFragment), which is registered in `widgetRepo.instances`. When undo is executed, editor's DOM is reloaded and the widget repository demolished, then re–built for the new DOM. Thus when `loadContent()` callback is executed, there's a brand new widget repository, which does not contain that initial temporary widget instance since it was located in docFragment. Finally `editor.widgets.finalizeCreation( temp )` is called. However, because `temp` belongs to a widget instance, which is no longer registered in the repository, the widget is not found and the error is thrown. **Cake recipe**: The fix should land in `embedbase`. `loadContent` should check if the widget still belongs to editor's widget repository first. **To–do**: Check if the fix covers the case when ""Source"" is pressed instead of ""Undo"".",Bug,closed,Normal,CKEditor 4.5.2,UI : Widgets,4.5.0,fixed,,