A website hosted in Plesk shows Internal Server error 500: Allowed memory size of XXX exhausted

Symptoms

• Website hosted in Plesk is inaccessible or an operation on a website fails:

  CONFIG_TEXT: 500 Internal Server Error

• The following error may occur when the WordPress domain is not accessible:

  CONFIG_TEXT: There has been a critical error on your website.
  Learn more about debugging in WordPress.

• The following error is shown in the website's log:

  CONFIG_TEXT: PHP Fatal error: Allowed memory size of XXX bytes exhausted (tried to allocate XXX bytes) in C:\Inetpub\vhosts\example.com\httpdocs\wp-config.php on line 91

  Note:
  On Linux: /var/www/vhosts/system/example.com/logs/error_log
  On Windows: %plesk_vhosts%\example.com\logs\php_errors\example.com\php_error.log

Cause

The website doesn't have enough memory allocated to be processed.

Resolution

1. Log in to Plesk GUI

2. Go to Domains > example.com > PHP Settings and increase memory_limit value according to the application requirements, using the instructions from the following article: How to change PHP memory_limit value via Plesk?

   Note: the following shortcuts should be used for memory_limit value: K (kilobytes), M (megabytes), and G (gigabytes). If "free -mh" command shows not enough RAM, contact your Cloud hosting provider to increase it