Every WordPress site has errors. PHP warnings, database connection failures, plugin conflicts, memory limit exhaustion — the list of things that can go wrong is long. The difference between a site that quickly recovers from errors and one that crumbles under them is monitoring.
Error logging and monitoring give you visibility into what’s happening on your site. They transform invisible failures into actionable data. This guide covers how to set up logging for development, staging, and production environments.
Development Debugging: WP_DEBUG
The foundation of WordPress debugging is WP_DEBUG. When enabled in wp-config.php, it displays PHP errors, warnings, and notices directly on the page. This is essential for development but should never be enabled on a production site where it could expose sensitive information to visitors.
Enable WP_DEBUG_LOG to write errors to a debug.log file in your wp-content directory instead of displaying them on screen. WP_DEBUG_DISPLAY controls whether errors are shown in the HTML output. On staging environments, enable the log but disable display.
Plugin-Specific Logging
If you’re a plugin developer, your plugin should have its own logging system. Use error_log() for simple logging, or better, implement a logger class that writes to a dedicated log file in the WordPress uploads directory.
Log important events like payment processing, API requests, scheduled task execution, and user authentication. Include timestamps, severity levels, and contextual data — the IP address, user ID, and relevant parameters that help you reproduce the issue.
Structured Logging with Monolog
For serious plugins, use the Monolog library. Monolog provides structured logging with severity levels, formatted output, and multiple handlers. You can log to files, databases, email, or external services with a consistent API.
Install Monolog via Composer and create a logger instance in your plugin’s initialization. Set different logging levels for development and production — DEBUG for development, ERROR for production. Add context data to each log entry to make debugging easier.
Production Monitoring with Sentry
Sentry is a production error tracking service that captures exceptions and errors from your site in real time. It provides stack traces, user context, and browser information for every error. The WordPress plugin for Sentry integrates seamlessly with WP_DEBUG and captures PHP errors, JavaScript errors, and performance data.
Set up Sentry on your production site by installing the Sentry WordPress plugin and configuring your DSN (Data Source Name). Errors are captured and sent to Sentry’s dashboard where you can view, group, and prioritize them. Sentry’s issue tracking helps you identify which errors affect the most users and fix them in priority order.
Performance Monitoring with New Relic
New Relic provides application performance monitoring for WordPress. It tracks page load times, database query performance, external API call times, and PHP execution details. New Relic’s transaction traces show you exactly which functions are slow and how much time each one consumes.
Install the New Relic PHP agent on your server and enable it for your WordPress site. The agent automatically instruments WordPress and provides detailed performance data without requiring code changes.
Health Checks with WP-CLI
WP-CLI provides built-in health check commands that test your WordPress installation for common issues. Run wp health check to see a summary of your site’s health, including PHP version checks, plugin compatibility, and database status.
Schedule regular health checks with cron to catch issues before they cause problems. Send alerts when health checks fail. The wp health check –all flag runs a comprehensive test that covers everything from disk space to plugin updates.
The Bottom Line
You can’t fix what you can’t see. Error logging and monitoring give you visibility into your WordPress site’s health, whether you’re running a single site or managing hundreds. Start with WP_DEBUG for development, add structured logging to your plugins, and deploy Sentry or New Relic for production monitoring. The time invested in setting up monitoring will be repaid many times over in faster debugging and fewer surprises.