"There has been a critical error on this website" in WordPress: Causes & Solutions

As a WordPress expert, I’ve frequently encountered the alarming “There has been a critical error on this website” message. This error, which became a standard feature in WordPress 5.2, is a major improvement over the notorious “white screen of death” (WSOD), providing users with an actionable error message.

While it may seem daunting to site owners, the critical error message is actually a step forward in WordPress error handling. It keeps the site partially functional while giving administrators the necessary tools to troubleshoot the issue.

This article will cover the causes, diagnosis, and solutions for this critical error, offering a comprehensive guide to fixing it and preventing future occurrences.

Understanding the WordPress Critical Error

The critical error message is part of WordPress’s built-in fatal error protection. When a fatal PHP error occurs—an error severe enough to stop the PHP script—WordPress intercepts it and displays a generic user-friendly error message instead of crashing the entire site.

In addition to showing the error on the front end, WordPress sends an email to the site administrator containing specific details about the issue. This email typically includes the problematic file, line number, and a brief description of the error, which helps in pinpointing the root cause.

This mechanism replaces the earlier WSOD error, which simply left users with a blank screen and no information, and helps admins quickly address the underlying issues.

Common Causes of the Critical Error in WordPress

The critical error can be triggered by various factors, ranging from conflicts between plugins and themes to server-related issues. Understanding the root causes will help you identify and resolve the problem more effectively. Below are the most common culprits:

1. Plugin Conflicts

• Plugins are often the source of critical errors, especially when they are poorly coded or incompatible with other plugins, themes, or the WordPress core. A single faulty plugin can bring down an entire site if it triggers a PHP fatal error.

2. Theme Conflicts

• Themes, like plugins, can introduce conflicts if they are outdated or poorly coded. Custom theme modifications, especially in files like functions.php, are common sources of errors.

3. PHP Version Mismatch

• WordPress and its plugins rely on specific PHP versions. If your hosting server is running an outdated version of PHP or your theme/plugin isn’t compatible with the latest PHP, a critical error is likely to occur.

4. Memory Limit Exhaustion

• Every WordPress site is allocated a certain amount of memory to execute PHP scripts. If a script exceeds the memory limit, it will trigger a fatal error, leading to the critical error message.

5. Core WordPress File Corruption

• Though rare, corruption in WordPress’s core files—often caused by failed updates or malware—can lead to critical errors.

6. Database Connection Issues

• If your WordPress site cannot connect to its MySQL database, the system cannot load critical data, causing the site to fail and display an error.

7. Syntax Errors

• If you recently edited any PHP file (e.g., functions.php), a single syntax error can prevent your WordPress site from running.

8. Server Configuration Changes

• Hosting environment changes, such as modifications to PHP configurations or server file permissions, can conflict with WordPress’s operational requirements.

Diagnosing the WordPress Critical Error

Before you can fix the critical error, you need to understand its cause. Here are some useful diagnostic steps:

1. Check Your Admin Email

• After a critical error occurs, WordPress automatically sends an email to the administrator containing details about the error. Look for an email with the subject line “Your Site is Experiencing a Technical Issue,” which will provide key information such as the specific plugin or file causing the issue.

2. Enable Debug Mode

• By adding define( 'WP_DEBUG', true ); to your wp-config.php file, you can turn on WordPress’s debug mode. This will display PHP error messages directly on your site, giving you more insight into the issue. You can also enable error logging by adding define( 'WP_DEBUG_LOG', true );, which logs errors to a file in the wp-content directory.

3. Check Server Logs

• Most hosting providers allow you to access error logs from your server’s control panel. These logs provide a more detailed look at the issues your site is encountering.

4. Use the Health Check Plugin

• WordPress’s official Health Check & Troubleshooting plugin helps diagnose the critical error by checking for common configuration issues and conflicts without affecting site visitors.

Solutions to the WordPress Critical Error

Once you’ve diagnosed the issue, it’s time to resolve the critical error. Below are detailed solutions for addressing common causes:

1. Deactivate All Plugins

• Access your site via FTP or the file manager in your hosting control panel and rename the wp-content/plugins folder to plugins_old. This deactivates all plugins. If your site becomes functional again, a plugin conflict is the likely cause. To find the specific plugin, reactivate them one by one through the WordPress admin.

public_html/wp-content/plugins -> public_html/wp-content/plugins_old

2. Switch to a Default Theme

• Rename your current theme folder (e.g., themes/your-theme to themes/your-theme-old) to force WordPress to revert to a default theme like Twenty Twenty-Four. If the issue is resolved, your theme is the source of the problem.

public_html/wp-content/themes/your-theme -> public_html/wp-content/themes/your-theme-old

3. Increase PHP Memory Limit

• Add define( 'WP_MEMORY_LIMIT', '256M' ); to your wp-config.php file to increase the PHP memory limit. This can resolve issues related to memory exhaustion.

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

4. Update PHP Version

• Outdated PHP versions can cause compatibility issues with WordPress. Contact your hosting provider to upgrade to a supported PHP version (ideally PHP 7.4 or higher). Updating your PHP version improves both security and performance.

5. Reinstall WordPress Core

• Corrupt core WordPress files can cause critical errors. Download a fresh copy of WordPress and replace the core files on your server, excluding wp-content and wp-config.php.

6. Check and Repair the Database

• Add define( 'WP_ALLOW_REPAIR', true ); to your wp-config.php file and navigate to www.yoursite.com/wp-admin/maint/repair.php to repair your database. This can resolve issues with corrupted database tables.

define( 'WP_ALLOW_REPAIR', true );

7. Restore from a Backup

• If you have a backup of your site, restoring it to a known-good state is often the fastest solution.

8. Fix Syntax Errors

• Review any recently edited PHP files, such as functions.php or wp-config.php, for syntax errors and correct them.

9. Check File Permissions

• Ensure correct file permissions: Directories should have 755 and files should have 644. Incorrect permissions can prevent WordPress from accessing necessary files, triggering errors.

10. Verify the .htaccess File

• Rename the .htaccess file to .htaccess_old to temporarily disable it. If this resolves the issue, you can generate a new .htaccess file by saving the permalinks settings in the WordPress admin.

Preventing Future Critical Errors

To avoid critical errors in the future, implement these best practices:

• Regular Backups: Use a backup plugin or your hosting provider’s backup service to create regular backups of your site.
• Staged Updates: Test updates on a staging environment before applying them to your live site.
• Quality Plugins and Themes: Use well-maintained, reputable plugins and themes from trusted developers.
• Keep Everything Updated: Regularly update WordPress core, plugins, themes, and PHP to their latest versions.
• Use Monitoring Tools: Set up uptime and performance monitoring to get alerts in case of issues.
• Enhance Security: Install security plugins and follow best practices to prevent unauthorized access or malware.

Advanced Troubleshooting Techniques

1. Enable Error Logging

• Add define( 'WP_DEBUG', true );, define( 'WP_DEBUG_LOG', true );, and define( 'WP_DEBUG_DISPLAY', false ); to your wp-config.php file to log errors without displaying them to site visitors. This will create a debug.log file in your wp-content folder with detailed error messages.

2. Check for PHP Version Conflicts

• Use plugins like PHP Compatibility Checker to scan your site for compatibility issues between plugins/themes and your PHP version.

3. Analyze Server Configuration

• Review PHP settings such as max_execution_time, post_max_size, and upload_max_filesize in your server’s php.ini file to ensure they meet WordPress requirements.

4. Use WP-CLI

• WP-CLI is a command-line interface for WordPress that lets you manage your site without needing the WordPress dashboard. Use commands like wp plugin deactivate --all and wp theme activate twentytwentyfour for troubleshooting.

5. Scan for Malware

• A security breach could trigger the critical error. Use a security plugin like Wordfence or Sucuri to scan for malware and clean your site.

When to Seek Professional Help

If you’ve tried all the above solutions and still encounter the critical error, it’s time to seek professional help. Consider:

1. Contacting your hosting provider’s support team
2. Hiring a WordPress developer or consultant
3. Seeking help from WordPress forums or communities

Provide them with as much information as possible, including:

• Error logs
• Recent changes to the site
• Steps you’ve already taken to troubleshoot

Conclusion

The “There has been a critical error on this website” message in WordPress, while alarming, is a helpful tool in diagnosing and resolving serious issues with your site. By methodically working through the potential causes and solutions outlined in this guide, you can often resolve the problem quickly and efficiently. Remember, prevention is always better than cure – regular maintenance, updates, and backups are your best defense against critical errors.