Debugging WordPress Theme: A Complete Guide for Developers and Site Owners
When something goes wrong with your WordPress theme, like layout glitches, broken features, or mysterious white screens, it can be frustrating. But don’t worry, with the right approach and tools, you can identify and fix most theme-related issues quickly.
This guide walks you through step-by-step methods for debugging a WordPress theme, whether you’re a beginner, designer, or seasoned developer.
Why Is Debugging WordPress Themes Important?
WordPress themes control the design and layout of your website. When a theme has issues, it can:
- Break your site’s appearance
- Interfere with plugins
- Create JavaScript or PHP errors
- Affect user experience and SEO
Debugging ensures your theme is stable, secure, and compatible with the latest WordPress updates.
Common Signs Your Theme Has Issues
Before diving into code, it’s helpful to recognize symptoms that point to theme-related problems:
- Pages not loading or displaying blank screens (White Screen of Death)
- Missing styles or layout breaks after updates
- Console errors in your browser’s Developer Tools
- PHP errors are in the logs or visible on pages
- Functions or shortcodes not working as expected
- Plugin conflicts after activating or updating a theme
If you notice any of these, it’s time to start debugging.
When something goes wrong with your WordPress theme, like layout glitches, broken features, or mysterious white screens, it can be frustrating.
But don’t worry, with the right approach and tools, you can identify and fix most theme-related issues quickly.
This guide walks you through step-by-step methods for debugging a WordPress theme, whether you’re a beginner, designer, or seasoned developer.
1. Enable WP_DEBUG in WordPress
The first step is to turn on debugging mode. This reveals hidden errors and warnings in your theme.
Open your wp-config.php file and find this line:
define('WP_DEBUG', false);
Change it to:
define('WP_DEBUG', true);
define('WP_DEBUG_LOG', true);
define('WP_DEBUG_DISPLAY', false);
This setup logs errors in /wp-content/debug.log without displaying them to users.
2. Check the Browser Console for Frontend Errors
Use your browser’s Developer Tools (usually F12 or right-click → Inspect → Console) to find JavaScript issues, failed AJAX requests, or missing files.
Look for:
- Red error messages
- 404s for CSS or JS files
- Conflicts between jQuery and other scripts
These often point to enqueued scripts/styles that are missing or misconfigured in your theme.
3. Switch to a Default Theme for Comparison
Temporarily activate a default theme like Twenty Twenty-five to see if the problem persists.
- If the issue disappears, your theme is likely the problem.
- If it stays, the problem may lie with a plugin or WordPress core.
You can switch themes safely via Appearance > Themes or by changing the template and stylesheet values in the database using phpMyAdmin.
4. Isolate the Problem with Plugin Conflicts
Sometimes it’s not just the theme—it’s a theme and plugin conflict.
- Deactivate all plugins
- Activate your theme
- Check if the issue persists
- Reactivate plugins one by one
This method helps identify the exact plugin causing conflict with your theme.
5. Validate Your Theme’s Code
Check your theme files for PHP, HTML, CSS, and JavaScript issues.
- Use the Theme Check plugin to catch common errors
- Validate HTML with W3C Validator
- Lint CSS and JavaScript for syntax problems
- Check for deprecated WordPress functions and bad coding practices
6. Use Query Monitor Plugin
Query Monitor is a powerful plugin that shows:
- PHP errors and warnings
- HTTP requests and API calls
- Enqueued scripts/styles
- Hooks and actions
- Database queries
This helps you see what’s failing in real-time and locate the file or function that’s misbehaving.
7. Look for Incorrect File Paths and Template Overrides
Sometimes themes fail because of misused file paths or improperly overridden templates.
Double-check:
- get_template_part() or locate_template() usage
- @import and enqueue_script() paths
- File existence for custom template files
- Child theme template overrides
A simple typo in a file name or path can break entire pages.
8. Debug Using Logs and Error Reporting
In addition to debug.log, you can enable server-side error logs via your hosting panel.
You can also add this to your .htaccess (if supported):
php_flag display_errors on
php_value error_reporting 32767
This forces PHP to show all errors—helpful in dev environments, but never used in production.
9. Check for Outdated or Incompatible Theme Code
If your theme was built a few years ago, it may not be compatible with the latest PHP or WordPress versions.
Look for:
- Deprecated functions (wp_get_theme_data(), get_theme_data(), etc.)
- Old jQuery syntax (.live() instead of .on())
- Removed WordPress hooks or filters
Keep your theme updated and refer to the latest WordPress developer documentation for best practices.
10. Enable SCRIPT_DEBUG for Troubleshooting
WordPress minifies its JS and CSS by default. To load the original unminified versions, add this in wp-config.php:
define('SCRIPT_DEBUG', true);
This helps when tracking down bugs in enqueued assets, especially in custom or bundled scripts.
Bonus Tip: Use a Local Development Environment
For more freedom in debugging, use a local dev environment like:
This allows you to enable all debugging settings without affecting your live site.
Conclusion
Debugging a WordPress theme isn’t as daunting as it seems, once you know what tools and techniques to use.
Start with enabling debug mode, check for browser and PHP errors, and methodically isolate the problem.
Whether you’re fixing layout issues, chasing down white screens, or resolving conflicts, this step-by-step approach will help you identify and fix the root cause efficiently.
Always back up your site before making changes, and consider working in a staging or local environment to avoid downtime.
Got a persistent issue? Share your debug steps with us, we might be able to help!
Happy Coding 🙂
How to Enable WordPress Debugging or Debug WordPress Theme
