A WordPress instance on Plesk fails with error 500: PHP Fatal error: Failed opening required '/var/www/vhosts/example.com/public_html/wordfence-waf.php'

Gabriel Aznarez

Updated February 13, 2024 12:40

Plesk for Linux kb: technical

Symptoms

A Wordpress instance site shows error 500.
The website has been migrated from cPanel.
The following errors can be found under Domains > example.com > Logs:

Warning 203.0.113.2 mod_fcgid: stderr: PHP Fatal error: Failed opening required '/var/www/vhosts/example.com/public_html/wordfence-waf.php'
There is a .user.ini file at the public_html root directory folder with the following instruction:

; Wordfence WAF
auto_prepend_file = '/var/www/vhosts/example.com/public_html/wordfence-waf.php'

WordFence plugin was removed from the WordPress instance but some leftovers of this still exist.

Edit the .user.ini file to comment the sentence that starts with "auto_prepend_file" by adding a semicolon (";") before like:

; Wordfence WAF
; auto_prepend_file = '/var/www/vhosts/example.com/public_html/wordfence-waf.php'

Command Line solution:

Connect to the server via SSH.
Run the following command while replacing example.com by the WordPress domain name:

# sed -i -e '/wordpress-waf.php/s/auto_prepend_file/;auto_prepend_file/' /var/www/vhosts/example.com/public_html/.user.ini