Unable to change the PHP settings when using LiteSpeed Web Server with Plesk

Symptoms

• LiteSpeed extension for Plesk is installed and LiteSpeed web server is activated.

• A website which has PHP executed as FPM application at Domains > example.com > PHP Settings is not loading with a 403 Forbidden error.

• A Magento-based website shows the following message while a supported PHP version is set in Plesk at Domains > example.com > PHP Settings:

  Magento supports PHP 7.0.2, 7.0.4, and 7.0.6 or later. Please read Magento System Requirements

• Changes in PHP Settings are not reflected on the phpinfo() page at Domains > example.com > PHP Settings > View the phpinfo().

• The following message appears on the Logs page (Domains > example.com > Logs):

  MIME type [application/x-httpd-php] for suffix '.php' does not allow serving as static file, access denied!

Cause

According to LiteSpeed documentation, currently the LiteSpeed PHP selector does not work with FPM applications.

Resolution

Switch from PHP-FPM to FastCGI:

1. Log in to Plesk.

2. Go to Domains > example.com > PHP Settings.

3. Switch PHP to FastCGI application.

4. Apply the changes.