WordPress plugin conflict? How to find and fix it

A WordPress plugin conflict happens when two plugins, or a plugin and your theme, try to change the same thing and break each other. The reliable way to find one is to switch off every plugin, switch to a default theme, then turn things back on one at a time until the problem returns. You can do that without visitors noticing by using a staging copy or the free Troubleshooting plugin. This guide covers both, plus what to do once you've found the culprit.

What does a plugin conflict look like?

Conflicts can look like many different problems. Watch for these signs:

• A blank white page, or the message "There has been a critical error on this website."
• Part of a page stops working: a slider that won't move, a menu that won't open on phones, a form that never sends.
• The block editor won't load, or buttons in the admin do nothing.
• Layouts shift after an update, with styles missing or doubled.
• Checkout fails on a WooCommerce site, often only for some payment methods.
• The site suddenly slows down after a plugin was added or updated.

If the problem started right after you installed or updated something, that's your first suspect. It isn't always the one at fault, though. A plugin update can expose a problem that another plugin or the theme was causing all along.

Why do WordPress plugins conflict?

Every plugin adds its own code to the same site. Most of the time they keep out of each other's way, and the clashes tend to come from a handful of situations.

The most common is two plugins doing the same job. Two caching plugins, two SEO plugins or two security plugins will often fight over the same settings and files.

Shared scripts are next. Plugins that load their own copy of the same JavaScript library, at different versions, can stop each other's features working on the page.

Optimization plugins cause their share too. Tools that combine and minify scripts can change the order code loads in, and a feature that worked before might break once its script runs too early.

Hosts also upgrade PHP from time to time. An old plugin that hasn't been updated in years may stop working on the newer version.

And some themes do too much. They bundle their own copies of plugins, or add features that overlap with plugins you've installed separately.

Before you start: back up and use staging

Take a full backup of files and database first. Many hosts offer one-click backups and a staging copy of the site. Staging is the safest place to test because nothing you do there touches the live site.

If your host has no staging, the Troubleshooting plugin is the next best option, because it limits changes to your own login session. It still runs on the live site, so take the backup anyway.

How to find a plugin conflict with Troubleshooting Mode

Troubleshooting Mode started as part of the Health Check plugin and is now also available as the standalone Troubleshooting plugin on WordPress.org. Its own description explains the idea: the most reliable way to troubleshoot WordPress is to disable all plugins and use a default theme, and Troubleshooting Mode tries to do that without affecting regular visitors.

To run it:

1. Install and activate the plugin from Plugins > Add New.
2. Turn on Troubleshooting Mode. With the Health Check plugin it sits under Tools > Site Health > Troubleshooting. Your session now runs with every plugin off and a default theme on.
3. Try to reproduce the problem. If it's gone, a plugin or your theme is the cause. If it's still there, the cause is more likely WordPress core, the server or the database.
4. Enable your theme from the Troubleshooting menu and test again. If the problem returns, the theme is involved.
5. Enable plugins one at a time, testing after each. When the problem comes back, the plugin you just enabled is part of the conflict.
6. Find the pair. Turn off everything except the suspect and test. If it works alone, add the others back one by one until it breaks again. That second plugin is the other half of the conflict.
7. Leave Troubleshooting Mode with the button in the admin bar. Signing out, clearing cookies for the site or closing all browser windows also ends it. The plugin's FAQ adds that some caching tools ignore Troubleshooting Mode, so clear your caches when you're done.

If you run a shop, be careful here. WooCommerce's own documentation notes that Troubleshooting Mode doesn't put payment gateways into test mode, so a real order placed during your session takes a real payment.

Can't get into wp-admin?

If the site shows a critical error and you can't log in, you have two options.

First, check your email. Since version 5.2, WordPress can detect fatal errors and email the site admin a link to recovery mode. That link lets you log in and deactivate the plugin it names.

If no email arrives, deactivate plugins by hand. Connect with SFTP or your host's file manager, open wp-content, and rename the plugins folder to something like plugins-off. WordPress will deactivate every plugin. Rename it back, then rename individual plugin folders one at a time to find the culprit.

Read the error log

A log often names the plugin and the file at fault, which can save an hour of switching things on and off.

The WordPress debugging guide shows how to turn on logging in wp-config.php. A common setup is these three lines:

• define( 'WP_DEBUG', true );
• define( 'WP_DEBUG_LOG', true );
• define( 'WP_DEBUG_DISPLAY', false );

Errors are then written to wp-content/debug.log and kept off the screen for visitors. The same guide says these tools are meant for local testing and staging, so on a live site switch them off again once you've found what you need. Your host's PHP error log is another place to look, and many control panels show it.

How do you fix a plugin conflict?

Once you know which plugins are involved, work through these choices, roughly in this order.

1. Update both plugins and your theme. Authors fix conflicts all the time, and the fix may already exist.
2. Check the plugin's support forum. Someone else may have reported the same pair, along with a workaround.
3. Report it to the plugin author. Include your WordPress and PHP versions, the other plugin involved and the steps to reproduce. Good bug reports get fixed faster.
4. Change a setting. If an optimization plugin is involved, excluding the affected script from combining or deferring often solves it.
5. Replace one of them. If two plugins do overlapping jobs, keep the better one.
6. Roll back to the last version that worked, temporarily, while you wait for a fix. Don't stay on an old version for long, since outdated plugins are a common way into WordPress sites.

How to stop conflicts happening again

You can't rule them out, but you can make them rarer and easier to spot.

• Run fewer plugins. Each one you remove is one less thing that can clash. Delete plugins you've deactivated, as well as switching them off.
• Update on staging first, then on the live site, a few plugins at a time so you know which one caused a problem.
• Avoid abandoned plugins. The WordPress.org listing shows when a plugin was last updated and which WordPress versions it's been tested with.
• Keep backups, and make sure you've tried restoring one.
• Be wary of heavy page builders. They load a lot of code on every page and touch everything, so they turn up in many conflicts.

When to get help

Some conflicts are quick to fix. Others point to a site that has grown fragile, where every update breaks something new. If that sounds familiar, a rebuild on a lighter theme may cost less over a year than fixing the same site again and again. Our WordPress service starts with a review of your theme, plugins and speed, and tells you whether fixes will do or a rebuild is worth it.

Sometimes a site starts behaving strangely without any update, with redirects to spam, unknown admin users or files you don't recognize. That usually means it was hacked, and a hack needs a different process, which we cover on our WordPress malware cleanup page. And if you'd like someone to handle updates for you, a care plan starts at $79 a month on our pricing page.

FAQ

How do I know if a plugin is causing a problem on my WordPress site?

Switch off all plugins and use a default theme, either on a staging copy or with Troubleshooting Mode. If the problem disappears, turn plugins back on one at a time. The one that brings the problem back is involved.

Does deactivating a plugin delete its settings?

Usually not. Deactivating a plugin stops its code running, and most keep their settings in the database until you delete the plugin. Some delete their data when you uninstall them, so check before you delete.

Can a plugin conflict break my whole site?

Yes. A fatal error in one plugin can show a white screen or a critical error message. WordPress may email the admin a recovery mode link, or you can rename the plugins folder over SFTP to switch them all off.

How many plugins is too many for WordPress?

There's no fixed number. One badly built plugin can cause more trouble than twenty well-maintained ones. Keep only plugins you use, avoid ones that do the same job, and remove anything that hasn't been updated in a long time. If you'd like a second opinion, send us a few lines about your site.