WordPress Debug: Fix Errors Like a Pro

WordPress Repair Guide · 2026

WordPress Debug:
Find & Fix Hidden Errors
Before They Kill Your Site

Your complete, no-fluff guide to turning on debug mode, reading error logs, and solving WordPress problems permanently.🩺 Get Free Error Diagnosis →

Something is broken on your WordPress site. You can feel it — slow pages, a weird error message, a feature that stopped working after a recent update.

The problem is, WordPress hides most of its errors by default. They are logged silently in the background, invisible to you — until the damage is already done.

That is exactly what WordPress debug mode is built for. It pulls the curtain back, shows you every PHP notice, warning, and fatal error, and gives you the information you need to fix things properly.

What Is WordPress Debug Mode?

WordPress debug mode is a built-in diagnostic switch that, when turned on, forces WordPress to surface every PHP error, notice, and warning that would otherwise be suppressed.

It is controlled by a single constant — WP_DEBUG — inside your wp-config.php file. When set to true, WordPress stops hiding problems.

Think of it as your site’s medical chart — it does not heal anything on its own, but it tells you exactly what is wrong so the right treatment can begin.

Why Most WordPress Errors Stay Hidden

DEFAULT STATE

WP_DEBUG = false

All errors suppressed — visitors see nothing wrong

DEBUG ON

WP_DEBUG = true

Errors surface — logged privately or shown on screen

💡 Official Reference: Read the full WordPress Debugging Documentation on WordPress.org — the authoritative guide maintained by the WordPress core team.

How to Enable WP Debug (Step-by-Step)

Turning on WordPress debug mode requires editing your wp-config.php file. Here is the correct, safe way to do it — especially on a live production site.

Access your wp-config.php file

Log in to your hosting control panel (cPanel, Plesk, or similar) and navigate to the File Manager. Find wp-config.php in your root WordPress directory.

Find the existing WP_DEBUG line

Look for the line that reads define( 'WP_DEBUG', false );. This is already there in every WordPress installation by default.

Replace it with the safe debug block below

Use this safe configuration — it logs errors to a file instead of displaying them to visitors:

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

Save the file and check for errors

Save the file and browse your site for a few minutes. Then navigate to /wp-content/debug.log to see every error that was recorded.

⚠️ Important: Always set WP_DEBUG_DISPLAY to false on a live website. Displaying raw PHP errors publicly exposes file paths and server details to potential attackers.

How to Read the WordPress Debug Log

The debug log file can look overwhelming at first — hundreds of lines of PHP warnings, notices, and errors. But once you understand the structure, it becomes very readable.

Every line in the log follows the same format: the date and time, the type of error, the message, and the file path plus line number where the error occurred.

Example debug.log entry

[16-Mar-2025 09:14:32 UTC] PHP Fatal error: Uncaught Error: Call to undefined function some_plugin_function() in /wp-content/plugins/broken-plugin/init.php on line 47

How to Decode This Line

Timestamp
Tells you exactly when the error happened — useful for tying it to a plugin update or a specific user action.

Error Type
Fatal error = site is broken. Warning = something is wrong but the site still loads. Notice = minor issue, often harmless.

File + Line
Points you directly to the broken file and the exact line number — this is where the fix needs to happen.

If you see the same plugin file appearing repeatedly in your log, that plugin is the culprit. Deactivate it, and the error chain stops immediately.

Common WordPress Errors Found Through Debug

WordPress error debugging typically surfaces the same categories of problems over and over. Here are the most common ones — and what each one actually means.

1
PHP Fatal Error — Call to undefined function

A plugin or theme is calling a function that does not exist — usually because a required dependency plugin is missing or deactivated.

Fix: Install the missing dependency, or deactivate the offending plugin shown in the debug log file path.

2
PHP Warning — Cannot modify header information

Output is being sent to the browser before WordPress finishes setting its HTTP headers — common in poorly coded plugins with whitespace before the opening PHP tag.

Fix: Open the file named in the log and remove any blank space or characters appearing before <?php.

3
Allowed Memory Size Exhausted

A PHP process ran out of the memory allocated to it — typically showing up as a blank white screen or an incomplete page render.

Fix: Add define('WP_MEMORY_LIMIT','256M'); to your wp-config.php and identify the bloated plugin causing the spike.

4
Database Query Error

WordPress is sending a malformed SQL query to your database — which usually means a plugin is incompatible with your current database version.

Fix: Enable SAVEQUERIES in debug mode to identify which query is failing, then update or replace the plugin responsible.

🔗 Related: If these errors are already causing a broken or crashed site, our team at Website Ka Doctor handles full WordPress error repair — including 500 errors, white screens, and plugin conflicts — with a same-day fix guarantee.

Best WordPress Debugging Tools in 2026

The built-in WP debug log is powerful, but there are several additional WordPress debugging tools that make error diagnosis significantly faster and more visual.

🔍 Query Monitor

The most powerful free debugging plugin for WordPress. It displays database queries, PHP errors, hooks, HTTP requests, and slow queries — all in a clean admin panel overlay. Essential for any serious debug session.

🐛 Debug Bar

Adds a dedicated debug panel to your WordPress admin toolbar. Pairs with extension plugins to display AJAX calls, rewrite rules, and transient cache data — giving you full visibility into what each page request actually does.

📋 WP Log Viewer

Reads your debug.log file directly inside the WordPress dashboard — no FTP access required. Colour-codes entries by severity so fatal errors stand out immediately at a glance.

⚡ Health Check & Troubleshooting

An official WordPress plugin that lets you troubleshoot plugin conflicts without affecting your live site. It disables all plugins and switches to a default theme — only for your logged-in session, keeping visitors unaffected.

💡 Free Tool: Download Query Monitor on WordPress.org — it is free, actively maintained, and used by professional WordPress developers worldwide.

Frequently Asked Questions

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

No — never enable debug with DISPLAY set to true on a live site. It will show raw PHP errors, file paths, and database details to every single visitor. Always log to a private file using the safe configuration shown above.

Where is the WordPress debug log file stored?

By default it is saved to /wp-content/debug.log on your server. You can access it via FTP, cPanel File Manager, or SSH. Some security-conscious setups move this file outside the public web root.

Can WordPress debug mode fix errors automatically?

No. Debug mode reveals errors — it does not fix them. You still need to interpret each log entry and make the correct change. If you are not comfortable reading PHP error logs, that is exactly what our repair service is built for.

Should I leave debug mode on permanently?

No. Once you have found and fixed the issue, set WP_DEBUG back to false. A permanently active debug log grows to a very large file size over time and marginally slows your site down.

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Debug Logs Too Confusing?
We Read Them For You — And Fix What’s Wrong.

Our team at Website Ka Doctor diagnoses WordPress errors every day. We read the debug log, identify the root cause, and fix it permanently — usually within 2–4 hours.

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Website Ka Doctor

India’s #1 WordPress Repair & Maintenance Expert

We have diagnosed and fixed over 500 WordPress sites across India — from blogs and landing pages to WooCommerce stores. Our speciality is finding what others miss and fixing it permanently. Based in Mohali, serving all of India remotely.