Handler “PHP55_via_FastCGI” has a bad module “FastCgiModule” in its module list

If you get this message when trying to run a PHP web app on IIS it is very likely that you have installed the PHP module using web platform installer but have forgotten to turn the CGI windows feature on in your OS configuration.

so go to control panel -> Programs And Features -> Turn windows features on/off -> Internet Information Services -> World Wide Web Services -> Application Development Features

and finally tick CGI. right here:

php cgi error