Curated resource guide
WordPress Debugging and Profiling Resources
Move from guesswork to evidence when diagnosing WordPress failures and slowdowns. This collection covers logs, Query Monitor, Xdebug, browser tools, database analysis, API and cron debugging, PHP profiling, APM, intermittent faults, and production-safe techniques for finding the real source of a problem.
Scope
What this guide covers
- WP_DEBUG and related constants
- debug.log
- PHP error logging
- Query Monitor
- Debug Bar
- Xdebug
- stack traces
- breakpoints
- database query analysis
- HTTP API debugging
- REST API debugging
- AJAX
- cron
- hooks
- object cache
- transients
- rewrite rules
- permissions
- fatal-error recovery
- browser DevTools
- JavaScript errors
- network waterfalls
- PHP profiling
- slow query logs
- APM tools
- production-safe debugging
- memory leaks
- race conditions
- intermittent issues
- and reproducible troubleshooting workflows
Selected references
Curated resources
Links open the original publisher so you can use the complete, current material in context.
- 01Recommended starting point
Debugging in WordPress
Official guidance for debug constants, logs, script diagnostics, and safe investigation during local development.
developer.wordpress.org - 02
Query Monitor
See query timing, PHP errors, HTTP requests, hooks, scripts, and request context while diagnosing WordPress.
wordpress.org - 03
Xdebug Step Debugging
Configure breakpoints and request triggers to inspect WordPress execution instead of adding temporary output.
xdebug.org - 04
Xdebug Profiler
Collect call-level timing and memory profiles for evidence-based backend performance work.
xdebug.org - 05
PHP Error Reporting
Use the PHP runtime reference when selecting diagnostic levels across development and production.
php.net - 06
Chrome DevTools Performance
Record browser work, network activity, layout, scripting, and rendering while debugging frontend behavior.
developer.chrome.com - 07
Debug Bar
Add a lightweight WordPress admin debug panel that other diagnostic extensions can integrate with.
wordpress.org - 08
Health Check and Troubleshooting
Inspect environment health and isolate theme or plugin conflicts in a session that does not disrupt normal visitors.
wordpress.org - 09
WP-CLI Doctor
Run configurable diagnostic checks against WordPress, PHP, files, cron, updates, and operational assumptions.
github.com - 10
Chrome DevTools Network Panel
Trace request timing, caching, headers, payloads, initiators, failures, and waterfall dependencies in the browser.
developer.chrome.com - 11
MySQL Slow Query Log
Capture slow database statements and administrative operations with deliberate thresholds and review controls.
dev.mysql.com - 12
WordPress Monitoring
The official WordPress overview of file, traffic, behavior, and integrity signals worth watching.
developer.wordpress.org