I had the same problem with Visual Editor’s hyperlink not working. I tested all my plugins and discovered the problem for me was “Constant Contact”. I deactivated the “Constant Contact” plugin, then all works fine. I will now have to find a solution to have a Constant Contact form on my site that integrates with CC.
Hope this may help someone else!
Warning errors Fixed. I added “error_reporting(0);” to the wp-config.php just below the following and it stop the warning errors. It also stopped the warning errors when changing the permalinks settings.
/** Sets up WordPress vars and included files. */
require_once(ABSPATH . 'wp-settings.php');"
error_reporting(0);
