I have the same problem on a couple of sites whilst trying to update JCE.

When I tried to update it says: Error updating package.

Now the joomla back end shows an error message: Class 'WFApplication' not found

If I try and install manually it says: Joomla\Filesystem\File::delete: Failed deleting inaccessible file editor_plugin.js

Other plug ins updated correctly and permissions are set to 755 / 644. I've also checked the ownership is correct.

Any ideas?

For the one I mentioned in my post it's 2.6.35.

There are also two others that use 2.6.38 that return a server error after attempting to update.

Also a fourth that uses 2.6.8 that doesn't show up in the update lists and outputs the following error on the JCE component page:

Warning: require_once(/xxx/public_html/administrator/includes/toolbar.php): failed to open stream: No such file or directory in /home/24544-79900.cloudwaysapps.com/xcahhvtczs/public_html/administrator/components/com_jce/controller.php on line 131

Fatal error: require_once(): Failed opening required '/xxx/public_html/administrator/includes/toolbar.php' (include_path='/home/24544-79900.cloudwaysapps.com/xcahhvtczs/public_html/plugins/system/shlib/shl_packages//ZendFramework-1.11.7-minimal/library:.:/usr/share/php:/usr/share/pear') in /home/24544-79900.cloudwaysapps.com/xcahhvtczs/public_html/administrator/components/com_jce/controller.php on line 131

I get an error message when trying to uninstall JCE:

Joomla\Filesystem\File::delete: Failed deleting inaccessible file mediajce.xml

Would manually deleting the folders and reinstalling fix this or does it need to be done via the joomla installer?

Have tried with both 775/664 and 755/644 but same issue.

Just to update this. It's only the JCE plug in that I'm unable to uninstall - I just tried installing and then uninstalling another plug in and had no issues.

Yeah that works - thanks. It's weird though because I checked the owner of those folders and it was correct, as were the permissions. I've also not had any issues updating before (the sites were migrated but it was a good year or two ago).

One last issue is the site that is returning the following error - is the procedure the same or is this unrelated?

Warning: require_once(/xxx/public_html/administrator/includes/toolbar.php): failed to open stream: No such file or directory in /home/http://24544-79900.cloudwaysapps.com/xcahhvtczs/public_html/administrator/components/com_jce/controller.php on line 131

Fatal error: require_once(): Failed opening required '/xxx/public_html/administrator/includes/toolbar.php' (include_path='/home/http://24544-79900.cloudwaysapps.com/xcahhvtczs/public_html/plugins/system/shlib/shl_packages//ZendFramework-1.11.7-minimal/library:.:/usr/share/php:/usr/share/pear') in /home/http://24544-79900.cloudwaysapps.com/xcahhvtczs/public_html/administrator/components/com_jce/controller.php on line 131