What should you do if a WordPress plugin displays an error, or your WordPress site isn’t functioning as it should?

This article addresses how to fix WordPress problems caused by plugin conflicts after upgrading, installing, or activating a new plugin or theme, or upgrading the WordPress platform.

Advice to solve a recent plugin problem

A recent visitor to our website asked for some advice on dealing with a WordPress problem they were having, stating that they weren’t ‘savvy’ in these matters. The problem they were having was a WordPress plugin was causing an error and actually locking them out of the WordPress Admin screen so that they could not login to fix the problem!

Plugins don’t always play nice

It is important to note that not all plugins ‘play nice’ by working together with other plugins or themes. When plugins don’t work well with other plugins or themes you have a ‘plugin conflict’.

WordPress plugins can often ‘throw errors’ or cause conflicts with other plugins or themes since they are made by many different 3rd parties.

If an error or problem does occur on your WordPress site it typically happens after upgrading, installing, or activating a new plugin or theme, or upgrading the WordPress platform itself.

After activating or upgrading a plugin within Wordpress, it is not uncommon for WordPress to display an error like the following somewhere on your Admin screen or sometimes even within your website:

Fatal error: Call to undefined function is_site_admin() in /home/public_html/wordpress/wp-content/plugins/my-plugin-folder/my-plugin-page.php on line 195

But even if a plugin doesn’t throw an error that doesn’t necessarily mean that everything is OK. You still may have a conflict with another plugin or possibly your WordPress theme that may be ‘breaking’ your website by causing other plugins or functionality to stop working properly.

Always test your website after any upgrades or changes

It may be very obvious or maybe not so obvious that other functions of your website aren’t working properly, so…

It is very important and highly recommended that after upgrading, installing, or activating a new plugin or theme (or making any other changes to your website or theme templates) that you take the time to experiment with and thoroughly test your website and even your Admin screens to make sure that your site (and backend) still looks and functions as it should.

How to test for problems with your website

The best way to verify that your site is working as it should is to keep another browser window (Control+N) or browser tab open (Control+T) to your website, then start clicking around your web pages and links while carefully observing how things look.

While browsing pages of your website make sure you refresh each page by using Control+R (Windows) or Command+R (Mac) to be sure you are not looking at an older cached page. To be really sure you are not looking at a cached page you can force a full page refresh by using Control+Shift+R (Windows) or Command+Shift+R (Mac). This takes a little longer to reload each page, but if you aren’t sure you are looking at a fresh reloaded page this is sometimes necessary.

Dealing with plugin errors and plugin conflicts

Try deactivating plugins

Sometimes problems caused by plugin errors or plugin conflicts are not ‘show stoppers’ and will allow you to continue using your WordPress website without any significant functionality problems.

If after activating or upgrading a plugin and you get an error, one way to test to see if it is OK for you to leave a plugin activated try going back one screen (Alt+Left Arrow (PC) or Command+Left Arrow (Mac)) from the plugin screen, then refresh the page to see if the error message goes away.

In this case if the error message goes away and it looks like the plugin is installed and activated (even if you received an error saying the plugin did not activate successfully), you are probably OK to leave that plugin activated, if not you probably want to deactivate or delete the plugin. (If it looks like the plugin activated OK but the upgrade or install caused an error it may be that the installation script threw an error, but maybe the plugin will still work. It is up to you at that point to take a chance by leaving the plugin activated/installed or not).

But on some occasions a plugin error or conflict can break your website or even lock you out of your Admin Dashboard when trying to login.

If this happens, don’t panic… since we are talking about WordPress there is an easy solution to get your website working again!

What should you do if you are having problems with a plugin? In an effort to diagnose and fix the problem with your website the first thing to try is to deactivate any plugin that you recently upgraded, installed, or activated (you may also want to deactivate other plugins as well, even if not recently upgraded or activated). Of course if your plugin won’t even allow you to login to the Admin screen then deactivating plugins is not an option.

If you recently changed themes you can also try reverting to the default WordPress theme (“Kubrick”) for testing purposes. If it isn’t obvious that your problem went away you may need to once again test your website to see if it is working properly or not.

If you can’t narrow down which plugin is causing the problems and your site is still broken (it could even be a plugin that has been installed and working properly for a while until something else changed), continue deactivating plugins (and possibly revert to the default WordPress theme for de-bugging purposes) until you can identify the culprit.

Delete the offending plugin

Once you have identified which plugin is causing misery in your life, and if deactivating the conflicting plugin did not fix your problem, the next step you should take is to DELETE the offending plugin entirely. Deleting a plugin may sound radical, but it is a step I have had to take several times, and it always works (thank you, WordPress). This may be the only option you have if you are locked out of your Admin login.

The best way to delete the plugin is by deleting the whole folder that the plugin created within your plugin directory on the remote server. To access remote files you can use the File Manager within the Control Panel available within your web host, or you can use an FTP client to access the remote files on the server in order to delete the offending plugin.

There are many FTP clients available, some of them even free (search Google if you need more):

• FileZilla
• CyberDuck
• Coda (Mac)
• CuteFTP
• SmartFTP
• Dreamweaver

If you are using FireFox for your browser I highly recommend the FireFTP extension.

The path to your plugin folder on the remote server will look something like this:

public_html/wordpress/wp-content/plugins/my-plugin-folder-name/

Once you have deleted the entire plugin folder then logging into Admin should work fine. Gratefully, WordPress responds to deleted plugins very well…if you are on the plugins screen you will see a note displayed at the top of the screen notifying you that a plugin has been deleted, and amazingly WordPress works just fine after deleting a plugin.

Since WordPress handles deleting plugins so gracefully WordPress makes it easy to want to constantly experiment with more plugins to add more functionality to your website. So go ahead and play around with plugins and themes, just be sure to backup your site now and then for safe measure.

Live without the offending plugin

If you have a plugin that just won’t cooperate, you probably have to live without the offending plugin, or at least maybe until the plugin author releases an upgrade that works for you.

You may want to send a note with any error messages or problems you are having with a particular plugin or theme to the comment form of the author’s homepage to expedite resolution to the error or conflict.

If the plugin offers functionality that I feel I really can’t live without, or it was a plugin that worked for a while then stopped working after a recent upgrade, I will sometimes leave the plugin ‘installed’, but NOT ‘activate’ it.

The benefit of this arrangement (leaving a plugin ‘installed’, but NOT ‘activated’ ) is that as long as an offending plugin is not activated it usually will not break your site, and you get the benefit of WordPress telling you when an upgrade to the plugin is available (via notification next to the plugin within the plugin screen) in the event you want to give it another go in hopes that the upgrade solves the problem you were having before.

Of course, you may find that the problem persists even with the latest plugin release, in which case you have to to through the whole cycle of things again that I already mentioned in order to alleviate the problem.

Still getting errors when upgrading or installing plugins?

If you continue to get errors every time you attempt to install a plugin, check to see if the error is related to a memory limit issue having to do with WordPress. In this case the error may look something like:

Fatal error: Allowed memory size of 67108864 bytes exhausted (tried to allocate 1816813 bytes) in /home/public_html/wp-includes/wp-db.php on line 499

Try changing the configuration value for your WordPress database memory allocation within the wp-settings.php file within the root directory of your WordPress install.

Find the line of code that looks like this:

define('WP_MEMORY_LIMIT', '64M');

And change the 64M to 128M. When I had this problem I adjusted the memory limit from 64M to 128M (or even 256M), and it solved my problem so that I was able to install plugins without any issues. 

Cheers, I hope this article has helped someone. Please let me know if it has helped you or if you have anything to add by leaving a comment on this site.

~Jeff Kemp

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