Enabling Debug Mode

Enabling WordPress Debug Mode

Edit wp-config.php:

// Add before "That's all, stop editing!"

// Enable debug mode
define('WP_DEBUG', true);

// Log errors to debug.log file
define('WP_DEBUG_LOG', true);

// Hide errors from display (security)
define('WP_DEBUG_DISPLAY', false);
@ini_set('display_errors', 0);

// Log database queries (optional)
define('SAVEQUERIES', true);

Viewing Debug Logs

Log file location:
/wp-content/debug.log

// View last 50 lines via SSH
tail -n 50 wp-content/debug.log

// View in real-time
tail -f wp-content/debug.log

Plugin-Specific Debug Mode

// Enable plugin debug logging
Settings → Attributes User Access → Advanced
☑️ Enable Debug Logging

// View plugin logs
Users → Attributes User Access → Logs

Common Error Messages

Fatal Error: Call to undefined function

Cause: Missing PHP extension or WordPress function

Fix: Check system requirements, enable required extensions

Warning: Cannot modify header information

Cause: Output before headers sent

Fix: Remove whitespace/echo before wp-config.php opening tag

Notice: Undefined index

Cause: Accessing array key that doesn’t exist

Fix: Usually harmless, can be ignored or reported

Collecting Debug Information

Tools → Site Health → Info
Export information for support ticket:
- WordPress version
- PHP version
- Active plugins
- Theme
- Server environment

Disabling Debug Mode

// After troubleshooting, disable debug
define('WP_DEBUG', false);
define('WP_DEBUG_LOG', false);

// Delete debug.log file
rm wp-content/debug.log