Troubleshooting WordPress Critical Errors: A Comprehensive Guide

Overview

Quick Actions Checklist

1. ✔️ Enable error logging

2. ✔️ Review recent site changes

3. ✔️ Check error logs

4. ✔️ Implement basic fixes

Prerequisites

• cPanel access credentials

• FTP credentials (if applicable)

• Recent backup available (WPCloud maintains automatic backups)

• List of recent site changes

• Admin access to WordPress (if available)

Understanding Critical Errors

Common Causes

Error Messages and Their Meaning

// Common error message patterns
Fatal error: Allowed memory size of 33554432 bytes exhausted
// ⬆️ Memory limit issue

Fatal error: Uncaught Error: Call to undefined function
// ⬆️ Missing function or plugin conflict

Fatal error: Maximum execution time of 30 seconds exceeded
// ⬆️ Script timeout issue

Diagnostic Process

1. Enable WordPress Debug Mode

// Add these lines before "/* That's all, stop editing! */"
define('WP_DEBUG', true);
define('WP_DEBUG_LOG', true);
define('WP_DEBUG_DISPLAY', false);
@ini_set('display_errors', 0);

2. Access Error Logs

Location of Important Logs

• WordPress Debug Log: /wp-content/debug.log

⚠️ Important Note: This log file will only be created and visible after enabling WP_DEBUG_LOG in wp-config.php

• PHP Error Log: /error_log

• Admin Error Log: /wp-admin/error_log

Understanding Error Types

🔍 Critical Note: WordPress critical errors almost always appear as PHP Fatal Errors in the logs. While you may see warnings and notices, these can generally be safely ignored during critical error troubleshooting.

[20-Nov-2024 15:30:45 UTC] PHP Fatal error: Uncaught Error:
Call to undefined function wp_get_current_user()
in /home/username/public_html/wp-content/plugins/example-plugin/main.php:120

Resolving Critical Errors

Common Solutions

1. Plugin-Related Issues

1. Navigate to /wp-content/plugins/

2. Rename plugins folder to plugins.deactivated

3. Check if site loads

4. If site loads, rename folder back to plugins

5. Deactivate plugins individually by renaming each plugin folder:
• Example: woocommerce to woocommerce.testing
• Example: elementor to elementor.testing

6. Test site after each plugin deactivation

7. Once you identify the problematic plugin, you can either:
• Update the plugin
• Contact plugin developer
• Find an alternative plugin

💡 Tip: Keep track of which plugins you've tested by maintaining the .testing suffix until you've identified the issue

<https://yoursite.com/wp-admin/?safe_mode=1>

• Temporarily disables all plugins

• Maintains your theme settings

• Allows admin dashboard access

• Helps isolate plugin-related issues

• Doesn't deactivate plugins permanently

• Doesn't affect your live site for regular visitors

• Doesn't change any settings

• Doesn't affect your database

💡 Tip: Safe Mode is particularly useful when you can't access wp-admin due to a plugin conflict but don't have File Manager access.

2. Theme-Related Issues

1. Navigate to /wp-content/themes/

2. Rename your active theme folder (e.g., mytheme to mytheme.deactivated)

3. WordPress will automatically switch to a default theme

⚠️ Important: This method will not affect your theme settings or customizations

3. Memory Limit Issues

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

Advanced Troubleshooting

1. Database Connection Issues

define('DB_NAME', 'database_name');
define('DB_USER', 'database_user');
define('DB_PASSWORD', 'database_password');
define('DB_HOST', 'localhost');

2. PHP Version Conflicts

1. Access cPanel's PHP Selector

2. Note current PHP version

3. Check plugin/theme requirements

4. Switch version if needed

Prevention Strategies

1. Regular Maintenance Checklist

• ✔️ Keep WordPress core updated to WPCloud's recommended version (check support portal for current recommendations)

• ✔️ Update plugins and themes during low-traffic periods

• ✔️ Monitor PHP error logs weekly

• ✔️ Test site functionality after updates

2. Development Best Practices

// Add to wp-config.php during development
define('WP_ENVIRONMENT_TYPE', 'development');

// Remove or set to 'production' for live site
define('WP_ENVIRONMENT_TYPE', 'production');

When to Contact Support

Immediate Support Required

• ❌ Database connection errors persist

• ❌ Critical error remains after trying all solutions

• ❌ File system permissions issues

• ❌ SSL/HTTPS related errors

Preparing Support Information

1. Error log contents

2. Recent changes timeline

3. Steps already attempted

4. Current PHP version

5. List of active plugins

Recovery Options

1. Using WPCloud Backups

1. Select the most recent working backup

2. Choose restore options:
• Full site restore
• Files only
• Database only

2. Manual Recovery Steps

1. Download fresh WordPress copy

2. Replace core files:
• wp-admin folder
• wp-includes folder
• Root WordPress files (except wp-config.php)

Best Practices Moving Forward

1. Testing Environment

• Test updates before applying to live site

• Verify plugin compatibility

• Check theme modifications

2. Regular Health Checks

1. Review error logs

2. Check available updates

3. Monitor disk space

4. Verify backup integrity

5. Test critical functionality

Support Contact Methods

• Support Portal: support.wpcloud.ca

• Email: support@wpcloud.ca

• Response Time: Typically within 15 minutes

Conclusion

1. Enabling debug logging

2. Identifying the error source

3. Applying appropriate solution

4. Implementing preventive measures