Codemirror plugin gives DOM error

[Marcus Bointon]

My CKEditor is working nicely, except when I click the source button, it throws this error, after which everything is broken.

[Error] InvalidCharacterError: DOM Exception 5: An invalid or illegal character was specified, such as in an XML name.
	add (ckeditor.js, line 79)
	(anonymous function) (ckeditor.js, line 79)
	loadCodeMirror (plugin.js, line 543)
	(anonymous function) (plugin.js, line 468)
	g (ckeditor.js, line 226)
	B (ckeditor.js, line 226)
	s (ckeditor.js, line 226)
	(anonymous function) (ckeditor.js, line 227)

I'm using vanilla CKEditor 4.5.1 with several standard plugins, including codemirror, using latest codemirror 5.4. It's nothing to do with the content inside the editor because it throws the same error even when there is no content at all.

The same config worked fine with CKEditor 4.4.8.

[Jakub Ś]

If you try the same without ​http://ckeditor.com/addon/codemirror plugin then source mode works.

This should rather be reported to plugin author and it is the plugin which needs to be adjusted to the editor and not the other way around.