WordPress Error 500 Guide

What is error 500 (Internal Server Error)

Error 500 indicates that the server could not complete the request. In WordPress, the most frequent causes involve plugins/themes, .htaccess, PHP limits or deprecated functions.

Log examples (anonymized)

These extracts show common patterns. Paths and domains have been anonymized.

[Sat Feb 08 12:03:17 2026] PHP Fatal error:  Uncaught Error: Call to undefined function get_magic_quotes_gpc() in /var/www/example/wp-content/plugins/old-plugin/init.php:42
Stack trace:
#0 /var/www/example/wp-settings.php(409): include()
#1 /var/www/example/wp-config.php(96): require_once('/var/www/exampl...')
#2 /var/www/example/wp-load.php(50): require_once('/var/www/exampl...')
#3 /var/www/example/wp-blog-header.php(13): require_once('/var/www/exampl...')
#4 /var/www/example/index.php(17): require('/var/www/exampl...')
thrown in /var/www/example/wp-content/plugins/old-plugin/init.php on line 42

[Sat Feb 08 12:05:02 2026] .htaccess: Invalid command 'php_flag', perhaps misspelled or defined by a module not included in the server configuration

[Sat Feb 08 12:06:45 2026] PHP Fatal error:  Allowed memory size of 134217728 bytes exhausted (tried to allocate 4096 bytes) in /var/www/example/wp-includes/class-wp-hook.php on line 310

How to intervene

• Enable logs and verify the exact error (file/line).
• Selectively disable suspicious plugins/themes.
• Restore standard WordPress .htaccess.
• Increase memory_limit and check deprecated functions.
• Confirm PHP version compatibility.

For general overview see WordPress Troubleshooting. For PHP incompatibilities consult WordPress PHP Update.