Debugging a possible clash between plugins and/or a theme

from one of my favourite comics

Put your site into maintenance mode and then Disable any caching plugins and be aware you may need to clear your browser cache too, to ensure you are  seeing ‘new’ behaviour when you are testing.

Quick and Brutal Approach (gives you info the fastest)

deactivate all plugins except the plugin you trying to get working. This has the advantage of quickly telling you if the plugin does/does not work by itself:

  • Problem gone when just that plugin?  The plugin itself might still be causing the clash, but at least now you have some info to pass on to the developers.  Follow the’ problem gone’ after theme switch below.
  • Problem still there ? Switch to a default theme.  Themes do sometimes mess with wordpress operation.
    • Problem still there ? If you now have just the one plugin active and you are sure you are seeing updated pages, you can advise the plugin author that you are seeing the problem on a default wp theme and with no other plugins active.
    • Problem gone? Ok,  now go back to your theme.
      • If the problem reappears you know it is something clashing between your theme and the plugin.  Advise both authors with as much detail as you can.
    • Problem still gone now that you have your theme back?  Now slowly, checking after each activation, reactivate your plugins, starting with your most essential ones.  At some point the problem will re-occur, then you know the clash is between the most recently activated plugin and your new problem one.
    • Problem stays gone once all is reactivated? Weirdly this can happen.  Sometimes it is the order of activation that causes the problem.  Don’t close your eyes and celebrate – a plugin update could cause the problem to come back.  Now you may have to play around with activation sequences here to find the clash

Slow and Steady also gets there in the end

Another approach is step by step deactivation and  switch theme to default theme until the problem disappears.

At some point the problem may go away, then reactive the last plugin active and check if the problem comes back.   Now you know it is part of the ‘clash’ somehow.

Must use plugins

If you have plugins showing up as ‘must use’ plugins and the problem is still there after deactivating other plugins and using default theme, you may need to use ftp or your control panel file manager to temporarily move the must use plugins in case there is code in there that is causing the clash.

Warning for older themes, or perhaps not so well written themes

Most themes should keep their settings and widgets and all should be fine when you switch back to that theme.  There some that don’t.  Make sure you have a backup that you know how to restore from OR that you know your theme’s settings and what widgets were being used where.

Recently Active Plugins

Your temporarily deactivated plugins will be in ‘recently active’.   This makes it really easy to reactivate them.

If you are one of those folks who keeps a lot of deactivated plugins hanging around and you forget which ones you really need, don’t panic – WordPress very nicely gives you a week in which it remembers which plugins you had active recently.