You have read or been told that you need to perform exhaustive troubleshooting with WordPress.
You'll need to be able to access the WordPress admin to follow these steps. If you are unable to access the WordPress admin area to disable plugins, you can still disable individual plugins forcefully by renaming its folder using the Plesk File Manager. Or you can disable all plugins by following the database trick described in the WordPress FAQ: FAQ Troubleshooting | WordPress.org.
A quicker solution may be found in our article on reducing dynamic processing with WordPress. It highlights the most common performance issues that might help resolve your problem. If not, then continue on with the exhaustive search!
Resolving issues with Exhaustive Search
Create a Backup? To proceed, you will need to deactivate parts of the site in order to troubleshoot the issue, and while this typically does not result in data loss, we strongly recommend backing up the site first.
Use a staging copy? If you do not wish for this troubleshooting to affect your live site, instead of taking a backup, you will need to clone the site to a staging environment and then proceed with the steps below on the staging copy of the site rather than the live site. Once you have identified the code which is causing the problem, you can then deactivate, remove, or replace it on the live site as well.
Go to Plugins in your WordPress admin. If you have a caching plugin active, it's best to disable it during this testing, but do not forget to re-enable it after. If it's a high traffic site, it's best to use a staging copy to prevent visitors from overwhelming resources while you're testing things. Now pick one of the following two approaches to proceoed:
Exhaustive troubleshooting with one plugin at a time
Deactivate the first plugin in the list, clear your cache (if using a caching plugin), then test the site to see if the issue is fixed. If it's not, re-activate the plugin then move on to the next one in the list. If it is, then you've found your problem: the last plugin you deactivated.
Exhaustive troubleshooting with all plugins at once (faster)
Deactivate all plugins then re-activate each one (excluding caching plugins), testing the site after each re-activation. When the issue comes back, you've found your culprit: the last plugin you activated. You can then re-enable all plugins you had previously been using and and request help from the developer of the plugin that you identified as causing the problem.
If deactivating all plugins does not resolve the issue: you will likely need to activate another theme (switch themes), even if just temporarily, to figure out if the theme code is to blame. If changing themes fixes the problem, then you should request help from the theme developer, or if you have had custom code written for the theme that might be to blame, talk to the developer that wrote that code.
If deactivating all plugins and switching your theme to the most recent WordPress default theme does not solve the issue, open a ticket to have us investigate, but if we don't see all plugins deactivated and the theme at default, we will ask you to do that before we proceed.
