How to Enable Error Logging in WordPress

Introduction

Error logging is an indispensable tool for any WordPress developer or administrator seeking to diagnose, troubleshoot and maintain a stable website. By capturing PHP errors, warnings and notices, you gain visibility into malfunctioning code, deprecated functions, plugin conflicts and performance bottlenecks.

Why Enable Error Logging

• Silent Failures: PHP errors often occur without visible symptoms logs reveal hidden issues.
• Security: Instead of displaying errors to visitors, logs keep sensitive details private.
• Performance: Detect and address resource-intensive warnings.
• Quality Assurance: Monitor deprecated functions before major upgrades.

Prerequisites

• Access to your WordPress installation files (via FTP/SFTP or hosting file manager).
• A code editor to modify wp-config.php or php.ini.
• Optional: Access to server logs (e.g. via cPanel or SSH).

Core Method: Using WP_DEBUG Constants

1. Open wp-config.php

Locate the wp-config.php file in your WordPress root directory.

2. Enable Debugging

// Enable WP debugging
define(WP_DEBUG, true)

// Log errors to wp-content/debug.log
define(WP_DEBUG_LOG, true)

// Prevent errors from showing on screen (production)
define(WP_DEBUG_DISPLAY, false)

// Optional: Force script concatenation off
define(SCRIPT_DEBUG, true)
  

After saving changes, WordPress will create or append to wp-content/debug.log.

3. Location of the Log File

The debug.log file resides in wp-content/. Ensure it is writable (chmod 660 or 644 depending on your server).

Alternative Methods

Method	Configuration File	Pros	Cons
PHP.ini	php.ini	Logs all PHP errors server-wide.	Requires server access affects all sites.
.htaccess	.htaccess	Easy if php.ini is inaccessible.	May not be supported on all hosts.
WordPress Plugin	N/A	UI-driven, no code edits.	Potential overhead plugin dependency.

Enabling via php.ini

error_reporting = E_ALL
log_errors = On
error_log = /path/to/your/site/php-error.log
display_errors = Off
  

Restart your web server after edits. Check /path/to/your/site/php-error.log.

Enabling via .htaccess

php_flag log_errors On
php_value error_log /home/username/public_html/php-error.log
php_value error_reporting 30711
  

Using Debugging Plugins

• Query Monitor (wordpress.org/plugins/query-monitor): Monitors PHP errors, database queries, hooks and more.
• Debug Bar (wordpress.org/plugins/debug-bar): Adds a debug menu showing query, cache, and PHP error data.

Server-Level Error Logs

Many hosts provide a “Logs” section in cPanel or Plesk. You can view:

• Apache/Nginx error.log
• PHP-FPM logs
• Access logs for HTTP status codes

Connect via SSH and tail logs in real time:

tail -f /var/log/apache2/error.log
tail -f /var/log/php-fpm/www-error.log
  

Customizing PHP Error Levels

Fine-tune which errors are logged:

// In wp-config.php or plugin/bootstrap file
error_reporting(E_ALL  ~E_DEPRECATED  ~E_STRICT)
ini_set(log_errors, On)
ini_set(error_log, dirname(__FILE__) . /wp-content/custom-errors.log)
  

Analyzing and Managing Log Files

• Rotation: Prevent files from growing indefinitely. Use logrotate on Linux:

/path/to/wp-content/debug.log {
  daily
  rotate 7
  compress
  missingok
  notifempty
  create 640 www-data www-data
}
  

• Monitoring: Integrate with services like Sentry for real-time alerts.
• Security: Ensure debug files are not publicly accessible. Deny via .htaccess:

  Require all denied

  

Best Practices and Security Considerations

• Never leave WP_DEBUG_DISPLAY enabled on production.
• Regularly review and purge old logs.
• Restrict file permissions and directory access.
• Document and track recurring errors in your issue tracker.

Troubleshooting Common Issues

• No debug.log generated Verify WP_DEBUG and WP_DEBUG_LOG are true
  and file permissions allow writing.
• Errors still displayed Ensure WP_DEBUG_DISPLAY is set to false.
• php.ini overrides Some hosts disallow local php.ini use .htaccess or plugin methods.

Further Reading

• WordPress Developer: Debugging in WordPress
• PHP Manual: error_log()
• WordPress Codex: Debugging in WordPress