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How to Enable Debug Mode in WordPress: Step-by-Step Guide

Posted on by William Zheng

Ever wondered why your WordPress site sometimes acts up, leaving you guessing what went wrong? You’re not alone—debugging is a crucial skill for anyone managing a website. Knowing how to enable debug mode in WordPress can help you track down errors, improve site performance, and keep everything running smoothly.

In this article, we’ll walk you through the simple steps to turn on debugging, share useful tips, and highlight what to watch out for along the way.

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How Does WordPress Enable Debug Mode?

If you’re running a WordPress website and encounter unexpected errors, white screens, or plugin conflicts, debugging becomes essential. WordPress comes packed with built-in debug mode features that allow you to catch and diagnose issues quickly. Enabling debug mode helps you pinpoint what’s going wrong behind the scenes, making it easier to fix errors before they impact your site’s visitors.

Let’s break down exactly how WordPress enables debug mode, why you should use it, how to enable it step by step, and some best practices to ensure you debug safely.

Understanding WordPress Debug Mode

WordPress debug mode is a powerful tool for developers, designers, and site administrators. At its core, debug mode reports and displays errors, warnings, and notices that would otherwise remain hidden. It’s like turning on a spotlight for issues lurking in your site’s code.

There are several debug-related constants and functions in WordPress, with the primary one being WP_DEBUG. Additional settings can further customize how errors are handled and displayed.

Why Enable Debugging in WordPress?

Before diving into the steps, it helps to know why you might want to enable debug mode:

  • Identify Coding Errors: Spot PHP errors, deprecated functions, and incorrect template use.
  • Troubleshoot Plugin & Theme Issues: See exactly where and why plugins or themes break.
  • Enhance Development: Streamline the development process for custom themes or plugins by quickly catching errors.
  • Improve Site Performance: Resolve issues that can slow down your website.

Remember: While debug mode is invaluable, it should generally be enabled on staging or development environments, not live sites, unless necessary for troubleshooting.

Step-By-Step: How to Enable Debug Mode in WordPress

You don’t need advanced knowledge to enable debug mode; a bit of familiarity with your hosting file manager or FTP client will suffice.

1. Locate Your wp-config.php File

  • The wp-config.php file sits in your site’s root directory.
  • Access it via cPanel File Manager, FTP/SFTP, or a local development environment.

2. Open the File for Editing

  • Use a text editor (like Notepad, Sublime Text, or your hosting’s online editor).
  • Always create a backup before making any changes.

3. Enable Basic Debug Mode

Find the following line (or add it if it doesn’t exist):

define( 'WP_DEBUG', false );

Change false to true:

define( 'WP_DEBUG', true );

With this change, WordPress will begin reporting PHP errors and warnings on your site.

4. Hide Error Messages from Visitors (Recommended)

Directly showing errors on your public site isn’t ideal. You can tell WordPress to log errors to a file, not display them to visitors.

Add or update the following lines:

define( 'WP_DEBUG_DISPLAY', false );
define( 'WP_DEBUG_LOG', true );
  • WP_DEBUG_DISPLAY: Hides errors from site visitors.
  • WP_DEBUG_LOG: Saves errors to a log file named debug.log in your /wp-content/ folder.

5. Save the Changes

  • After updating and saving wp-config.php, errors will now be recorded and/or displayed, depending on your settings.

Details on Useful Debug Constants

Beyond WP_DEBUG, WordPress offers several helpful settings for various debugging requirements.

WP_DEBUG

  • Purpose: Master switch for debugging in WordPress.
  • Values: true (enable debugging), false (disable debugging).

WP_DEBUG_LOG

  • Purpose: Logs all errors to a file.
  • Default Location: /wp-content/debug.log.
  • Usage: Set to true to create or append to the log file.

WP_DEBUG_DISPLAY

  • Purpose: Controls whether errors are shown in-browser.
  • Values: true (display errors), false (hide errors).
  • Tip: For live sites, keep this set to false.

SCRIPT_DEBUG

  • Purpose: Forces WordPress to use unminified versions of CSS and JavaScript files.
  • Usage: Useful during development for easier debugging of front-end behavior.
define( 'SCRIPT_DEBUG', true );

SAVEQUERIES

  • Purpose: Logs all database queries for analysis.
  • Usage: Can affect performance, so use only when necessary.
define( 'SAVEQUERIES', true );

The above constants can be stacked within your wp-config.php file as needed.

Using Plugins to Enable Debugging

If you prefer a more hands-off approach, there are plugins that simplify enabling debugging. These plugins offer easy toggles for debug settings, often along with user-friendly error viewers. Examples include “Debug Bar” and “WP Debugging.”

Advantages of Using Plugins

  • No need to edit code manually.
  • Some plugins offer enhanced error viewing, filtering, and notifications.
  • Safer for those unfamiliar with FTP or code editors.

However, for critical troubleshooting, manually editing wp-config.php ensures accurate and real-time debugging.

Safety and Best Practices for Debug Mode

Enabling debug mode is a double-edged sword: it gives you visibility into problems, but can also expose sensitive information if you aren’t careful.

Do’s

  • Use Debug Mode on Staging Sites: Test and troubleshoot before making changes to your live site.
  • Log Errors Instead of Displaying Publicly: Avoid showing error messages to visitors for security and professionalism.
  • Monitor and Review Error Logs: Check /wp-content/debug.log regularly during development.
  • Disable Debugging When Done: Don’t leave debugging enabled on production sites.

Don’ts

  • Don’t Ignore Backups: Always back up your wp-config.php file and your database before making changes.
  • Don’t Share Error Logs Publicly: Logs may contain sensitive server paths or configurations.
  • Don’t Overlook Performance: Features like SAVEQUERIES can slow your site if left active.

Common Challenges When Debugging in WordPress

Debugging is powerful but can present its own set of challenges:

  • No Errors Appear: Some hosting environments suppress error output at the PHP or server level. Check PHP settings or consult your host.
  • Permission Issues: Ensure WordPress has write permission to /wp-content/ for creating the debug.log file.
  • Too Much Output: On heavily trafficked sites, debug logs can grow large quickly. Regularly clear logs when done debugging.
  • Plugin or Theme Conflicts: Sometimes, debugging reveals issues in multiple plugins or themes. Be systematic in troubleshooting.

Practical Tips and Expert Advice

  • Temporarily Switch to Default Themes: If debugging theme issues, activate a default WordPress theme (like Twenty Twenty-One) to isolate problems.
  • Deactivate All Plugins: Reactivate plugins one by one to find which is causing errors.
  • Consult the debug.log File: Read through errors line-by-line to spot patterns or repeated issues.
  • Use Staging Environments: Many hosting providers offer staging environments—use these for debugging without risking your live site.

Disabling Debug Mode

Once you’ve finished diagnosing and fixing issues, return all debug-related constants to false in wp-config.php:

define( 'WP_DEBUG', false );
define( 'WP_DEBUG_DISPLAY', false );
define( 'WP_DEBUG_LOG', false );

This keeps your website secure and professional for visitors.

Summary

WordPress debug mode is a must-have tool for anyone developing, managing, or troubleshooting websites. Whether editing wp-config.php manually or using a plugin, you can quickly surface errors that would otherwise remain hidden. With careful management—enabling logging, protecting sensitive info, and always turning debug mode off when done—you’ll keep your site healthy and running smoothly.

Frequently Asked Questions (FAQs)

1. How do I enable debug mode in WordPress?

To enable debug mode, edit your site’s wp-config.php file and set define('WP_DEBUG', true);. For smoother troubleshooting, also set WP_DEBUG_LOG to true to log errors, and WP_DEBUG_DISPLAY to false to prevent showing errors to visitors.

2. Where can I find the WordPress debug log file?

The debug log is saved as debug.log in the /wp-content/ directory of your WordPress installation. You can access and open this file using a file manager or FTP.

3. Is it safe to enable debug mode on a live site?

Debug mode should generally not be enabled on live/public websites since it can display sensitive error messages to visitors. If you must debug a live site, ensure WP_DEBUG_DISPLAY is set to false and only check errors via log files.

4. Can I enable debugging without editing files manually?

Yes, several plugins allow you to enable WordPress debug mode with a few clicks. Search for debugging plugins like “Debug Bar” or “WP Debugging” in your dashboard’s plugin repository.


The built-in WordPress debugging options - wordpress enable debug

5. What should I do after finishing debugging?

Always turn off debug mode in your wp-config.php file by setting all related constants (WP_DEBUG, WP_DEBUG_LOG, and WP_DEBUG_DISPLAY) back to false. This ensures errors aren’t logged unnecessarily and your site’s security is maintained.

By understanding and carefully managing WordPress debug settings, you gain a clearer view of what’s happening under the hood and can resolve issues efficiently, keeping your website secure and reliable.

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