Every WordPress site has errors. PHP notices, database query failures, plugin conflicts, server timeouts — they happen constantly. The difference between a well-maintained site and a neglected one isn’t the absence of errors; it’s knowing about them before your users do.
Error logging and monitoring give you visibility into what’s happening on your site. For plugin developers, this is especially important — you can’t fix bugs you don’t know about. This guide covers how to set up logging and monitoring at every level, from local development to production.
WP_DEBUG: The Foundation
WordPress’s built-in debugging system starts with WP_DEBUG. When enabled in wp-config.php, it displays PHP errors, warnings, and notices directly on the page. This is essential during development but should never be enabled on a production site.
For development environments, enable WP_DEBUG along with WP_DEBUG_LOG and WP_DEBUG_DISPLAY. WP_DEBUG_LOG writes errors to a file at /wp-content/debug.log, and WP_DEBUG_DISPLAY shows them on the page. For staging environments, enable WP_DEBUG_LOG but disable WP_DEBUG_DISPLAY — log errors for review but don’t show them to users.
Query Monitor: The Swiss Army Knife
Query Monitor is the most useful debugging plugin for WordPress development. It adds an admin toolbar that shows database queries, hooks, HTTP requests, block editor data, and PHP errors — all organized for easy inspection.
For plugin developers, Query Monitor’s database query panel is invaluable. It shows every query executed on the page, how long each took, and which function triggered it. This makes it easy to identify poorly performing queries, duplicate queries, and database bottlenecks.
Server-Level Error Logs
Your web server (Apache, Nginx, LiteSpeed) maintains its own error logs. These capture issues that happen before WordPress loads — PHP fatal errors, memory limit exhaustion, and server configuration problems that WP_DEBUG can’t catch.
Access server error logs through your hosting control panel or via SSH. Look for patterns: repeated PHP fatal errors, memory allocation failures, and 500 Internal Server Error entries. These logs are often the first place a problem appears, and checking them regularly can catch issues before they affect users.
Error Monitoring with Sentry
For production sites and plugins, a dedicated error monitoring service like Sentry is the gold standard. Sentry captures errors in real-time, groups similar errors together, and provides detailed context including stack traces, user data, and environment information.
For WordPress plugins, the Sentry PHP SDK can be integrated to capture errors that happen in your plugin’s code. Set up the SDK in your plugin’s initialization, configure it with your DSN (Data Source Name), and it will automatically report uncaught exceptions and PHP errors. Sentry’s WordPress plugin simplifies this integration further.
Uptime Monitoring
Uptime monitoring checks whether your site is accessible from multiple locations around the world. Services like Pingdom, UptimeRobot, and Better Uptime ping your site at regular intervals and alert you if it’s down.
Configure your uptime monitor to check your site every 1-5 minutes from at least two locations. Set up notifications via email, SMS, Slack, or your preferred channel. For plugin developers, uptime monitoring is important not just for your own site but for ensuring your plugin’s update server, API endpoints, and licensing system remain accessible.
Performance Monitoring
Performance monitoring tracks your site’s speed over time and alerts you when it degrades. Tools like Chrome User Experience Report, Lighthouse CI, and WebPageTest can be scheduled to run regular performance tests.
For plugin developers, performance monitoring helps catch regressions when you release new versions. A plugin update that adds an unoptimized query will show up in your performance metrics. Set up a performance budget — maximum page load time, maximum query count — and alert when your plugin exceeds it.
The Bottom Line
Error logging and monitoring are not optional for professional WordPress development. At minimum, enable WP_DEBUG_LOG on staging environments, install Query Monitor for development, and check your server error logs weekly. For production sites and plugins, invest in a service like Sentry for real-time error tracking and an uptime monitoring service for availability alerts.
The cost of monitoring is negligible compared to the cost of a bug that goes undetected for weeks. Errors happen. The question is whether you find them or your users do.