- Plesk Onyx 17.5 for Windows
PHP Settings button is available while no PHP handlers installed on a server and proper settings in service plan applied. This results in an error about missing handler:
PLESK_ERROR: Domain "example.com": the PHP handler "fastcgi-5.6" is not registered
Resources and permissions for the subscription cannot be customized with the same error as above.
This is Plesk bug #PPPM-6125 which was fixed in Plesk Onyx 17.8 and Plesk Onyx 17.5.
Perform an upgrade to Plesk Onyx 17.5 or Plesk Onyx 17.8.
If it is not possible to create a subdomain when there are no PHP handlers installed, check the article:
Cannot create subdomain: there are no available PHP handlers