A "critical error" message — or a completely blank white page — is WordPress's way of saying a script crashed while loading, usually seconds after a plugin or theme update. The good news: the site files are almost always fine, and recovery takes five minutes.
What usually causes it
- A plugin that just updated, was just activated, or is incompatible with your PHP or WordPress version.
- A theme (often newly activated) calling functions that don't exist.
- A server memory limit that's too small for what the plugin needs.
The quick fix: switch off the plugins folder
This is a blunt tool that proves whether plugins are the cause:
- Log into cPanel and open File Manager.
- Enter
public_html/wp-content. - Right-click the plugins folder and select Rename. Call it
plugins_off. - Load your website. If it comes back, plugins were the problem — the site now runs with none of them active.
To turn them back on one at a time, rename the folder to plugins again, then reactivate each plugin in the admin. As soon as the site breaks, you've found the culprit.
Get the actual error message
WordPress hides the real error. Turn on debugging to read it:
- In File Manager, open
public_html/wp-config.phpwith the edit tool. - Add these lines just above the "That's all, stop editing" comment:
define('WP_DEBUG', true);
define('WP_DEBUG_DISPLAY', true);
- Save and reload the site. A specific PHP error now shows instead of the white screen. Remove the two lines when you're done diagnosing.
If it says memory exhausted
Errors mentioning Allowed memory size exhausted need a bigger PHP memory limit. Raise it via cPanel's PHP settings (under Select PHP Version), increasing from the default to 256M. See PHP Versions Explained for where that sits.
When to restore
If a recent automated backup predates the problem, restoring is often faster than debugging. See How to Restore Your Website From a Backup. Otherwise, submit a ticket with the debug error text — it makes our team's job far quicker.