WordPress Troubleshooting Intermediate

Fixing WordPress 500 Internal Server Error

Diagnose and resolve a WordPress 500 error caused by .htaccess syntax errors, PHP fatal errors, plugin conflicts, memory limits, or corrupted files.

UnderHost NOC Network Operations

8 min read Updated June 2026

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Overview
Check the error log first
.htaccess syntax error
Plugin or theme conflict
PHP memory limit
File permission errors

A 500 Internal Server Error on WordPress means PHP or the web server encountered a fatal error before it could serve a page. The error itself doesn't tell you what went wrong-you need to look at the error logs to find the cause.

Check the error log first

In cPanel, go to Metrics → Errors. The error log shows recent PHP and server errors with the file and line number. This is the fastest way to identify the cause of a 500 error.

Alternatively, enable WordPress debug logging:

wp-config.php

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

Then check wp-content/debug.log for the error message. Remove or disable this after troubleshooting.

.htaccess syntax error

A corrupted or malformed .htaccess file is the most common cause of 500 errors after a plugin update or a .

Fix: In File Manager, rename .htaccess to .htaccess_old, then reload your site. If the 500 error disappears, the .htaccess was the cause.

To generate a fresh .htaccess, go to WordPress → Settings → Permalinks and click Save Changes without changing anything. WordPress regenerates it automatically.

Plugin or theme conflict

If the error occurred after installing or updating a plugin:

In File Manager, go to wp-content/plugins/
Rename the recently updated plugin's folder (e.g. bad-plugin → bad-plugin_disabled)
Reload the site
If the 500 error resolves, that plugin was the cause
Check for an updated version of the plugin or report the issue to its developer

For a theme conflict, rename the active theme folder in wp-content/themes/-WordPress will fall back to a default theme.

PHP memory limit

If the error log shows Allowed memory size of X bytes exhausted, increase PHP memory:

wp-config.php

define( 'WP_MEMORY_LIMIT', '256M' );

Also increase it in cPanel → MultiPHP INI Editor → set memory_limit to 256M.

File permission errors

If the error log shows "Permission denied" errors, check file permissions. WordPress files should be 644 (files) and 755 (directories). Permissions set to 000 or 777 can cause 500 errors. Fix via cPanel → File Manager → right-click → Change Permissions, or via SSH:

$ find ~/public_html -type d -exec chmod 755 {} \; && find ~/public_html -type f -exec chmod 644 {} \;

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