Warning when applying Performance Booster on a website on a Plesk server: Custom

[senthil]

Symptoms

• When using Performance Booster for a website, a warning is shown when trying to apply the option
  "Optimize PHP settings: Enables JIT compilation and the realpath cache":
  Custom PHP directives are specified in this domain's PHP settings.
  
• The website at Domains >example.com> PHP > Additional configuration directives already has some custom
  PHP directives.

Cause
Custom PHP directives are specified in this domain's PHP settings.

Resolution
Remove the custom directives and apply the optimization again:

• Log into Plesk dashboard.
• Go to Domains >example.com> PHP > Additional configuration directives
• Remove all directives (even ones added by Plesk) and click Apply.
• Go back to Domains >example.com> Performance booster and apply the settings again (the "Optimize
  PHP settings" option should now be available.)
• (Optional) If there were personal directives added to the domain, they can be re-added at
  Domains>example.com> PHP > Additional configuration directives.