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

Posted on by William Zheng

Ever found yourself stuck with a mysterious error on your WordPress site, unsure what’s causing the problem? You’re not alone. Whether you’re a casual blogger or a website manager, troubleshooting WordPress can save time, money, and frustration.

Understanding WordPress debug mode is the key to uncovering hidden issues and getting your site back on track. In this article, we’ll show you exactly how to enable debug mode, interpret the results, and share tips for effective troubleshooting.

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How to Enable WordPress Debug Mode: The Complete Guide

WordPress debug mode is an essential tool for uncovering errors, finding conflicts, and optimizing your website’s performance. Whether you’re a developer or a website owner, understanding how to enable and use debug mode can save you hours of troubleshooting and prevent headaches down the road.

In this complete guide, you’ll learn what WordPress debug mode is, how to turn it on (and off), practical tips for using it safely, and answers to common questions.

What Is WordPress Debug Mode?

WordPress debug mode, known as WP_DEBUG, is a built-in feature that helps you identify errors, warnings, and notices generated by WordPress, plugins, or themes. When enabled, it displays these messages, making it easier to spot problems that could affect your site’s stability and security.

Why Use Debug Mode?

  • Error Detection: Instantly see if plugins, themes, or custom code has issues.
  • Performance Monitoring: Find slow or deprecated functions slowing down your site.
  • Site Optimization: Clean up or replace non-recommended WordPress code.
  • Security: Prevent errors from exposing sensitive site information to visitors.

How to Enable WordPress Debug Mode

There are two main ways to enable debug mode: editing the wp-config.php file manually, or using a plugin. Both are safe if followed carefully.

Method 1: Manually Editing the wp-config.php File

This method is straightforward and puts the most control in your hands.

Step-by-Step Instructions

  1. Access Your Site Files
  2. Use an FTP client (like FileZilla) or your hosting provider’s file manager to open your WordPress root directory.

  3. Look for the file named wp-config.php.

  4. Open and Edit wp-config.php

  5. Download a backup copy of the file for safety.

  6. Open wp-config.php with a text editor (such as Notepad++ or VS Code).

  7. Find the Debug Section

  8. Search for this line:
    php
    define('WP_DEBUG', false);
    If it doesn’t exist, you can add it above the comment that says “That’s all, stop editing! Happy posting.”

  9. Enable Debugging

  10. Change the line to:
    php
    define('WP_DEBUG', true);

  11. To also log errors instead of showing them on the front end (recommended for live sites), add:
    php
    define('WP_DEBUG_LOG', true);
    This creates a debug log file in wp-content/debug.log.

  12. To hide error messages from visitors, add:
    php
    define('WP_DEBUG_DISPLAY', false);
    @ini_set('display_errors', 0);

  13. Save & Upload

  14. Save the changes and upload the file back to your server, overwriting the original file.

  15. Test Your Site

  16. Visit your website or perform the actions causing issues. Check for new error messages or the debug log file.

Example Debug Settings for Production (Live) Sites

define('WP_DEBUG', true);
define('WP_DEBUG_LOG', true);
define('WP_DEBUG_DISPLAY', false);
@ini_set('display_errors', 0);

Tip: Always turn off debug mode or hide errors after troubleshooting to prevent exposing site details.

Method 2: Using a Debugging Plugin

If you’re uncomfortable editing files, several plugins can help you enable debugging with a few clicks.

Common Debug Plugins

  • WP Debugging
  • Query Monitor
  • Debug Bar

How to Enable Debugging with a Plugin

  1. Log in to your WordPress dashboard.
  2. Go to Plugins > Add New.
  3. Search for a reputable plugin (e.g., “WP Debugging”).
  4. Install and activate the plugin.
  5. Follow the plugin’s instructions—usually, you’ll get toggles to enable or disable debug mode and view logs.

Note: Plugins automate changes in wp-config.php but check your settings after plugin activation to ensure debugging is set the way you want.

Understanding Debug Log Files

When WP_DEBUG_LOG is enabled, all debug messages are stored in a log file located at wp-content/debug.log.

Benefits of Using the Debug Log

  • Error Tracking: See errors that visitors don’t see.
  • Shareable Logs: You can share the file with developers or support for help.
  • Historical Record: Track when issues first appeared.

How to Read the Debug Log:

  • Download and open wp-content/debug.log in a text editor.
  • Look for entries marked with [ERROR], [WARNING], or [NOTICE].
  • Each entry will have a timestamp for easier troubleshooting.

Always Clear Logs After Use

Delete or clear the debug.log file regularly to avoid unnecessary storage usage and keep sensitive site information secure.

Best Practices and Precautions

Debug mode is powerful, but it needs to be used thoughtfully. Here’s how to get the best results safely:

Dos

  • Backup First: Always back up your site and database before making code changes.
  • Use Debug Log in Production: Avoid showing errors to visitors on a live site. Always log errors instead.
  • Disable Debug After Use: Leaving debugging on can expose security risks.
  • Check File Permissions: Ensure wp-content/debug.log is writable by the server.
  • Document Findings: Keep notes of any issues or warnings you identify for future reference.

Don’ts

  • Don’t Debug on Live Sites Publicly: Error messages may reveal sensitive paths or SQL info.
  • Don’t Ignore Errors: Use debug findings as a prompt to fix underlying code or plugin issues.
  • Don’t Forget to Reset: Set WP_DEBUG back to false when done.

Troubleshooting: If Debugging Doesn’t Work

If you don’t see error messages or a debug log after enabling debug mode:

  • Make sure you’ve saved wp-config.php properly and uploaded it to the correct directory.
  • Check for typos or incorrect placement of the debug statements.
  • Verify server file permissions and that wp-content is writable.

If using a caching plugin or server cache, clear it to ensure recent changes show.

Advanced Debugging Tools in WordPress

1. SCRIPT_DEBUG

WordPress uses minified CSS and JavaScript by default. Enabling SCRIPT_DEBUG forces WordPress to load the development (unminified) versions of core CSS and JS files, which can help you trace and debug front-end issues.

define('SCRIPT_DEBUG', true);

2. Deprecated Notices

You can also enable deprecated function notices to help update plugins and themes:

define('WP_DEBUG_DISPLAY', true);
define('WP_DEBUG', true);

Now, outdated functions and methods will be flagged for easier future-proofing.

Practical Tips for Smooth Debugging

  • Use Local or Staging Sites: Make troubleshooting safer by working on a copy of your site.
  • Work Incrementally: Enable/disable plugins or themes one by one to isolate problems.
  • Consult the Log: Use timestamps to map issues to actions performed on your site.
  • Do Regular Maintenance: Debug mode can reveal deprecated code that needs updating—don’t neglect these warnings.
  • Involve Professionals: Share the debug log with a developer if you’re unsure about errors.

Summary

Enabling WordPress debug mode is straightforward and an essential skill for website troubleshooting and development. By updating your wp-config.php file or using a plugin, you can quickly spot errors and optimize your site. Remember to use debug mode responsibly: back up your data, never display errors on live sites, and always turn off debugging once your work is done.

Frequently Asked Questions (FAQs)

1. What is the purpose of WordPress debug mode?
WordPress debug mode helps identify code errors, warnings, and deprecated functions from plugins, themes, or WordPress core. This makes troubleshooting easier and keeps your site running efficiently and securely.

2. Is it safe to enable debugging on a live site?
It’s safe if you use WP_DEBUG_LOG and set WP_DEBUG_DISPLAY to false, which logs errors privately instead of displaying them publicly. Never display errors on a live or production site, as this exposes sensitive information to visitors.

3. Where can I find WordPress error logs once debug mode is enabled?
If WP_DEBUG_LOG is set to true, WordPress creates a file called debug.log inside your site’s wp-content directory. You can access this file via FTP or your hosting file manager.

4. I turned debugging on, but nothing changed. What should I do?
Check that your edits to wp-config.php are correct and saved in the right location. Make sure there are no typos, and that wp-content is writeable by your server. Also, clear any caches your site or host may be using.

5. Do I need to leave debug mode enabled all the time?
No. Debug mode should only be enabled when you’re actively troubleshooting or developing. Leaving it on can create security risks and may clutter your site with unnecessary error logs or display unwanted messages to users.

WordPress debug mode is your ally in building faster, safer, and more reliable websites. With these tips and steps, you’re ready to handle errors like a pro!

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