Initial assessment
WordPress Error Cases

There has been a critical error on this website.

“There has been a critical error on this website.” in WordPress: causes and what to check

Updated 2026-10-30
# Common log entries
PHP Fatal error:  Uncaught Error: Call to undefined function …
PHP Fatal error:  Allowed memory size of … bytes exhausted

WordPress shows this message when PHP stops on a fatal error. The site content and database are usually intact; the error is in plugin, theme, or core code.

Which of these matches what you see?

Check the site admin email inbox for a message with the subject “Your Site is Experiencing a Technical Issue.” It contains a recovery mode link that opens the dashboard and names the plugin or theme that caused the error. If no email arrived or the link does not work, WP119 can locate and deactivate that plugin or theme on a copy of the site.

The error is in code that runs on public pages. Check whether a plugin or theme was updated shortly before the message appeared. If the recovery mode email arrived, it names the component.

The error is usually in a plugin feature used only on those pages, such as a form, store, or page builder element. Note the affected URLs; the initial assessment checks them.

Common causes

Plugin or theme updateA new version conflicts with another plugin or with the server's PHP version.
PHP upgrade by the hostOlder code calls functions removed in the newer PHP version. The log often shows “Call to undefined function.”
Memory limit reachedThe log shows “Allowed memory size of … bytes exhausted.”
Interrupted updateCore or plugin files were only partly replaced.

What the system does

White screens and fatal errors (plugin conflicts, PHP version incompatibility) are handled automatically: on a copy of your site in the recovery station, the system turns on debug mode, finds the plugin or theme causing the error and deactivates it (not deleted); a white screen caused by exhausted memory is fixed by raising the memory limit. After the fix, the home page and inner pages are re-verified, and only then is the result written back to your host (in WP admin mode, a recovered package is delivered instead).

  1. Initial assessmentEnter the site URL
  2. Copy to the recovery stationWork runs on the copy
  3. Find the causeItem-by-item checks
  4. Recover and re-checkHome and inner pages
  5. Write back or deliverOnly after re-checks pass

Use WP119 when the recovery email did not arrive, the dashboard does not load, or you prefer not to edit files on the server.

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