title: 404.3 Error for .php extensions on IIS 10
body: <p>I've used WEBPI to install PHP 7.1 on IIS 10 in an attempt to develop PHP on a local machine. I get this error when navigating to a .php file:</p>
  
  <p>HTTP Error 404.3 - Not Found
  The page you are requesting cannot be served because of the extension configuration. If the page is a script, add a handler. If the file should be downloaded, add a MIME map.</p>
  
  <ul>
  <li><p>CGI is activated</p></li>
  <li><p>ASP.NET is installed</p></li>
  <li><p>The handler is mapped in FASTCGI (C:\Program Files\PHP\v7.1\php-cgi.exe) in the IIS Manager</p></li>
  <li><p>HTTP Activation is ON</p></li>
  <li><p>aspnet_regiis.exe -ir has been run</p></li>
  </ul>
  
  <p>Why aren't PHP file extensions being recognized?</p>