Preserve the evidence first
The WordPress critical error screen indicates a fatal problem, but it does not identify the cause. Record the affected URL, time, last deployment and any error identifier. If available, use the recovery-mode email to access the administration area without assuming the named plugin is the only issue.
Take a recoverable backup of the files and database before changes. Preserve server and PHP logs securely: they can contain paths, personal data or tokens. Avoid displaying detailed errors to website visitors.
Narrow the failure
Check the PHP error log around the reported time and identify the first relevant fatal error and stack trace. Compare PHP version, active theme and plugin changes with the last known working release. A missing extension, incompatible update, exhausted resource or application bug can all produce similar public symptoms.
Reproduce the issue on a staging copy where possible. Deactivate or roll back one suspected component at a time using the supported method, and record the result. If administration is unavailable, follow the official recovery guidance or work with the host; do not delete a plugin's data blindly.
Restore service and verify
After a change, test the affected page, administrator login and a representative form or checkout in a controlled way. Review logs again and confirm that the same error has stopped. A rollback may require compatible database state; restoring an older plugin file alone does not necessarily reverse its database migration.
Keep a short incident timeline and arrange a permanent compatibility fix. If debugging is temporarily enabled, limit access to the log, avoid exposing errors publicly and return settings to the approved state afterward.
Further reading
Read the official documentation. For help applying these checks, explore Clouvenix services.