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WordPress Technical Guide

How to Fix Critical WordPress Errors? Recovery Mode and Fatal Error Guide

The “There has been a critical error on this website” message indicates that a fatal error was caught on the PHP side while WordPress was running, terminating the request. This guide explains the sequence of finding the error log, isolating plugin and theme sources, verifying PHP compatibility, and safely reopening the site.

Critical ErrorRecovery Modedebug.logPHP Fatal ErrorWP-CLI
root@server:~SSH
There has been a critical error on this website.
PHP Fatal error: Uncaught TypeError
wp-content/plugins/ornek-eklenti/ornek.php on line 84
WordPress LayerKernel, theme and plugin behavior.
PHP layerVersion, extension, limit, and fatal error
Server layerWeb service, database, disk, and logs
Secure MethodBackup, log, isolate, and verify
01
Technical description

What does a critical error message in WordPress mean?

WordPress Critical Error Screen Does Not Indicate the Root Cause Alone. The actual cause is usually found in the PHP error log, WordPress debug.log, or the file and line information in the email sent to the administrator in Recovery Mode.

WordPress 5.2 and later, may display a general critical error screen to the visitor by catching fatal PHP errors originating from a theme or plugin. The recovery link sent to the administrator's email helps to disable the problematic component.

If it started immediately after a plugin update, the first suspicion is that plugin; however, PHP version change, missing PHP extension, broken opcode cache, or function collision within the theme can also produce the same result.

WP_DEBUG should not be left exposed to visitors on a production site. Error details should be stored in files, not on the screen, and debug settings should be reverted to a safe state after the issue is resolved.

If the management panel is not opening, disabling the suspicious plugin via FTP, file manager, or WP-CLI is a more controlled first step than restoring the entire site to a previous backup.

Removing critical error message is not a success. The issue should not be considered resolved until it is confirmed that the same URL does not produce a new fatal error in PHP and web server logs.

02
Log messages and their meanings

Critical errors, fatal errors, and Recovery Mode messages

Search for the phrase you see in the email, browser, or SSH log. Each card includes meaning, probable cause, and safe initial action.

8 registration
01kritik

There has been a critical error on this website

Meaning: WordPress has terminated the request on the PHP side with a fatal error.

Possible cause: Plugin, theme, PHP version or missing extension.

Find admin email and the first fatal error line in debug.log.
02kritik

PHP Fatal error: Uncaught Error

Meaning: The code execution has been terminated without being caught.

Possible cause: Undefined class/function, incorrect parameter or version incompatibility.

Record file path and line number, and isolate related component.
03kritik

Uncaught TypeError

Meaning: A function has received an unexpected data type.

Possible cause: Old theme/plugin may be incompatible with new PHP version.

Compare PHP version and updated component.
04warning

Recovery Mode link expired

Meaning: The recovery connection has expired or has been used before.

Possible cause: Single-use link, cache, or incorrect site URL.

Create a new Recovery Mode email or disable the extension at the file level.
05kritik

Allowed memory size exhausted

Meaning: PHP has consumed the defined memory limit.

Possible cause: Heavy plugin, loop, large query, or low limit.

First, find the consuming file from the log; do not increase the limit blindly.
06kritik

Call to undefined function

Meaning: Code calls a non-existent function.

Possible cause: Missing PHP extension, unloaded file or incorrect plugin order.

Determine if the function is core or extension.
07kritik

Parse error: syntax error

Meaning: PHP file is not parseable.

Possible cause: Missing parenthesis, manual incorrect editing or half update.

Compare the file's clean version and verify its syntax.
08warning

The site is experiencing technical difficulties

Meaning: General fatal error notification in old WordPress versions.

Possible cause: Old text of the same critical error class.

Examine the PHP error log and wp-content/debug.log file.

No records matching this expression were found.

03
Secure first review

SSH diagnostic commands and what output to look for?

Commands are for root access. Collect only status and logs first; Do not change the permanent setting without seeing the reason.

WordPress and PHP version
wp core version
php -v

Displays core and CLI PHP version; note that web PHP may be different.

Last WordPress error logs
tail -n 150 wp-content/debug.log 2>/dev/null
tail -n 150 error_log 2>/dev/null

Finds the file and line information of the first file in the fatal error.

Eklenti durumu
wp plugin list --status=active

Lists active plugins and their versions.

Close the suspicious add-on
wp plugin deactivate EKLENTI-ADI

Only disables the specified extension in a controlled manner.

Theme and core validation
wp theme list
wp core verify-checksums

Shows the active theme and checks if core files have been modified.

PHP modules
php -m | sort

Missing mysqli, intl, mbstring or zip extensions.

04
By hosting environment

Controls to be applied on cPanel, Plesk and panelless server

The root cause of the WordPress error is the same, but log paths, PHP settings screens and service management vary depending on the hosting infrastructure used.

cPanel / WHM

cPanel's MultiPHP, File Manager, and Metrics > Errors sections are used.

  • Verify the actual PHP version of the domain from MultiPHP Manager.
  • Examine the wp-content/debug.log and error_log files using the File Manager.
  • Rename the suspicious extension folder only when necessary.
cd /home/KULLANICI/public_html && /usr/local/bin/wp plugin list --allow-root

Plesk Obsidian

Plesk PHP Settings, Logs, and WordPress Toolkit can be used together.

  • Find the PHP fatal error line in the Domains > Logs screen.
  • Check handler and version compatibility via PHP Settings.
  • Use WP Toolkit to disable the problematic plugin and re-check the site.
cd /var/www/vhosts/ALANADI/httpdocs && wp plugin list

Panel-less Linux Server

On a server without panels, the web PHP, PHP-FPM pool, and application log are examined together.

  • Sync Nginx/Apache and PHP-FPM logs at the same second.
  • Run WP-CLI with the web user.
  • Re-load the opcode cache or FPM pool only after log validation.
sudo -u www-data wp plugin list --path=/var/www/html
05
Safe solution order

Steps to safely resolve a critical error in WordPress

First record the error, then isolate the component; verify core and PHP compatibility and test the site in a controlled manner.

1

Record the error time and affected URL.

Home page, wp-admin, or only specific action, separate.

curl -sSIk https://example.com/
2

Enable debug logging securely

Write errors to the wp-content/debug.log file without displaying them on the screen.

3

Find the first fatal error line.

Focus on the first file and line information instead of the secondary error at the end of the chain.

tail -n 150 wp-content/debug.log
4

Isolate the problematic plugin or theme.

Disable the component seen in the log instead of deleting all extensions.

wp plugin deactivate EKLENTI-ADI
5

Verify PHP and core integrity.

Check the version compatibility, extensions, and checksum results.

wp core verify-checksums
6

Re-test the site and its administration panel

Verify that the error log does not produce new records and that cron tasks are running.

curl -sSIk https://example.com/wp-admin/
06
Distinction by symptom

Special scenarios and decision trees

Started after plugin update

Close the updated plugin, check the PHP requirements, and the change log.

wp plugin deactivate EKLENTI-ADI
Only wp-admin returns a critical error

Admin-specific extensions, high admin memory, and dashboard widgets are reviewed.

wp --skip-plugins user list
Occurred due to PHP version change

Verify that the target PHP version is supported by the theme and extensions.

php -v
Recovery Mode email is not received

WordPress mail system may not be working; proceed with file manager or WP-CLI.

wp option get admin_email
Site is sometimes opening and sometimes crashing.

Memory limit, FPM worker, cron, and concurrent requests should also be investigated.

wp cron event list

Absolutely don't

  • Do not delete all plugins without viewing the error file.
  • Do not leave display_errors open on the production site.
  • Do not modify wp-config.php without a backup.
  • Do not downgrade the theme or core to a random old version.
  • Do not revert the entire site to its old backup when the error source is unknown.
  • Do not leave plugin folders with permanent different names.

Post-solution verification

  • Home page and wp-admin return expected HTTP code.
  • new fatal error is not occurring in debug.log.
  • Active plugins and themes in expected versions.
  • Compatible with PHP version and application requirements
  • Cron and AJAX requests are working.
  • Recovery Mode temporary connection is no longer required
07
Official technical resources

WordPress and WP-CLI official documentation

08
Internal SEO content set

Related WordPress error solutions

09
Frequently asked questions

WordPress Critical Error Curiosities about

What causes a critical error in WordPress?

The most common causes are fatal errors in plugin or theme code, PHP version incompatibility, missing extensions, and memory exhaustion. The exact cause is determined by the file and line information in the log.

Recovery Mode what is?

WordPress's recovery mode, which provides a special link to the administrator to temporarily disable the theme or plugin causing a fatal error.

How do I disable the extension if the panel is not opening?

You can rename the related extension folder in FTP or file manager, or use the WP-CLI deactivate command for the plugin.

Should WP_DEBUG remain open?

In a production environment, it should not be left open and display error messages on the screen. It should be switched to a safe mode after the inspection is completed.

Is downgrading PHP version a solution?

May provide temporary diagnosis but the permanent solution is to update or replace the incompatible component.

Does critical error cause data loss?

Usually stops the request; does not delete data directly. However, incomplete orders, imports, or updates should be checked separately.

Which log should I look at?

Firstly, check wp-content/debug.log, domain PHP error log and web server's error log file.

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