There has been a critical error on this website

Is this your problem?

• The message "There has been a critical error on this website"
• A blank white page, sometimes only on some pages
• wp-admin shows the same error, so you cannot log in
• It started right after an update, or after the host changed PHP
• The error appears only when you edit a page in a page builder

What usually causes it

How to fix it, step by step

1. 1

   Check your email for the recovery link

   Since WordPress 5.2 the site emails the admin address when this happens. The subject is "Your Site is Experiencing a Technical Issue". It names the plugin or theme and has a special link that logs you in with that plugin paused. Use it to deactivate the plugin, then update or replace it.

2. 2

   Turn on the error log

   Open wp-config.php in your host file manager or over SFTP. Add these lines above the one that says "That is all, stop editing". The error is then written to wp-content/debug.log instead of the screen.

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   define( "WP_DEBUG", true );
   define( "WP_DEBUG_LOG", true );
   define( "WP_DEBUG_DISPLAY", false );

3. 3

   Read the last fatal error

   Open wp-content/debug.log and look for the newest line that starts with "PHP Fatal error". The file path in it tells you who is at fault: wp-content/plugins/NAME is a plugin, wp-content/themes/NAME is the theme.

4. 4

   Switch the plugin off without logging in

   In the file manager, rename the plugin folder, for example wp-content/plugins/NAME to NAME-off. WordPress deactivates it. If you cannot tell which plugin it is, rename the whole plugins folder to plugins-off, check the site loads, rename it back, and then turn plugins back on one at a time in wp-admin.

5. 5

   If it is the theme

   Rename the active theme folder. WordPress falls back to a default theme, as long as one such as Twenty Twenty-Four is still installed. If none is installed, upload one first.

6. 6

   If the host changed PHP

   Switch back to the previous PHP version in the host panel to get the site up, then update the plugin or theme that is not ready for the newer version and switch forward again. Staying on an old PHP version is a security risk, so treat it as a stopgap.

7. 7

   If it ran out of memory

   Raise the WordPress memory limit in wp-config.php. Your host may cap it lower, in which case ask them to raise the PHP memory_limit.

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   define( "WP_MEMORY_LIMIT", "256M" );

8. 8

   Turn the log off again

   When the site works, set WP_DEBUG back to false or remove the lines, and delete debug.log. Left on, the log file can reveal file paths to anyone who finds it.

Stop it happening again

• Test updates on a copy of the site before they go live.
• Update one plugin at a time and check the site after each one.
• Keep a daily backup you have actually restored once.
• Keep PHP on a version that still gets security fixes.