On Plesk for Linux server, website fails to open with error 500 or adding additional Apache directive fails: Invalid command, perhaps misspelled or defined by a module not included in the server configuration

Symptoms

• One of the following issues occurs on a Plesk for Linux server:

  1. A website fails to open with the error 500.

     The following error is found in Plesk in Domains > example.com > Logs or in the log file /var/www/vhosts/system/example.com/logs/error_log :

     [core:alert] /var/www/vhosts/example.com/httpdocs/.htaccess: Invalid command 'ExpiresActive', perhaps misspelled or defined by a module not included in the server configuration

  2. Adding a directive into the fields under Additional Apache directives in Domains > example.com > Apache & nginx Setting fails:

     PLESK_ERROR: Invalid Apache configuration: AH00526: Syntax error on line 1 of /var/www/vhosts/system/example.com/conf/vhost_ssl.conf: Invalid command ‘PassengerEnabled’, perhaps misspelled or defined by a module not included in the server configuration

• The Apache module from the error message is shown as disabled in Tools & Settings > Apache Web Server > Apache modules, for example:
  

Cause

The Apache directive used in the file .htaccess or attempted to be added as an additional directive is related to the disabled Apache module.

Resolution

Note: This article is intended for use by server administrators. In case there is no administrative access to the Plesk interface, contact the server administrator or server provider.

1. Log into Plesk.

2. Go to Tools & Settings > Apache Web Server.

3. In the section Apache modules, enable the module which is tried to be used by the directive (for example, expires).

4. Click OK or Apply to save the changes.

Additional information

How to enable the browser caching directive for the domain?