WordPress Debug Errors Showing on Website

Overview

WordPress debug mode is a development tool that outputs PHP notices, warnings, and errors directly to the screen. When WP_DEBUG is enabled on a live site, raw error messages and code references appear in place of normal page content, or alongside it — visible to every visitor.

Common Causes

WP_DEBUG set to true in wp-config.php on a production site
WP_DEBUG_DISPLAY not explicitly set to false
a plugin or theme activating debug mode as a side effect
a staging environment migrated to production with debug settings intact
a developer enabling debug mode to troubleshoot an issue and not reverting the change

How the Problem Appears

PHP notices, warnings, or deprecated function messages printed on the page
error messages containing file paths and line numbers visible in the browser
layout partially broken by injected error output
white screen with only error text
debug log entries appearing in page source

How It Is Diagnosed

reviewing wp-config.php for WP_DEBUG, WP_DEBUG_LOG, and WP_DEBUG_DISPLAY constants
checking whether errors appear for all users or only logged-in administrators
inspecting the page source for hidden error output
reviewing the wp-content/debug.log file for logged errors

Typical Fix

set WP_DEBUG to false in wp-config.php
set WP_DEBUG_DISPLAY to false to suppress screen output
optionally set WP_DEBUG_LOG to true to redirect errors to a log file instead
if the underlying PHP errors are legitimate, address the deprecated functions or plugin issues generating them

The correct production configuration in wp-config.php:

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

Technical Website Support

If debug errors are appearing on your live website, they should be resolved immediately — they expose internal file structure to visitors and indicate unresolved code issues.