I've just upgraded my WordPress site from 4.3.1 to 4.4, and I've just come across an issue which I've tested, and it does seem to happen upon upgrading the core from 4.3.1 to 4.4.

When I go into a post or page with a WYSIWYG editor, I cannot switch tabs between 'Visual' and 'Text'. Whatever the tab was before the upgrade, it's stuck on.

Anyone else had this issue?

(I think quite a few styles and scripts are loaded through the header.php so I'm going to move these to the functions.php file, registering them and enqueing them so I can load them only when not in the admin area.)

Here's the only JavaScript error: Uncaught TypeError: Cannot set property 'toolbar1' of undefined

  • Are you using Advanced Custom Fields Plugin? WYSIWYG included with WordPress should work perfectly. If I recall correctly, this bug happened with ACF few months back, have you updated it?
    – N00b
    Dec 23, 2015 at 14:26
  • I do have ACF, I just disabled it and the issue still occurs. Dec 23, 2015 at 14:29
  • Do you get any JS error on console?
    – Sisir
    Dec 23, 2015 at 14:30
  • That's the first thing I checked, and I saw nothing. However, now I get Uncaught TypeError: Cannot set property 'toolbar1' of undefined. Dec 23, 2015 at 14:31
  • 1
    This site has 22 plugins (sigh), I've just disabled them all and the issue is fixed. I guess one of these plugins is very outdated. I'll get back to you on which is the problem. Dec 23, 2015 at 14:44

1 Answer 1


A plugin was the cause of this issue, 'PS Disable Auto Formatting'. After disabling this plugin, the issue was fixed.

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