title: What causes an HTTP 405 "invalid method (HTTP verb)" error when POSTing a form to PHP on IIS?
body: <p>I have one form in a PHP (5.2.9-1) application that causes IIS (Microsoft-IIS/6.0) to throw the following error when POSTed:</p>
  
  <blockquote>
    <p>The page you are looking for cannot be displayed because an invalid method (HTTP verb) was used to attempt access.</p>
  </blockquote>
  
  <p>It's an HTTP 405 status code. All other forms in the application work, so I believe that the IIS 'verbs' setting for PHP pages is correct.</p>
  
  <p>This is a customer's server, which I have no access to for verifying settings or testing code. All I can do is send the customer replacement files. Other customers on IIS servers have no such issue.</p>
  
  <p>The form is perfectly straightforward:</p>
  
  <pre><code>&lt;form method="post" action="index.php"&gt;
      ... fields ... 
  &lt;/form&gt;
  </code></pre>
  
  <p>What can cause IIS to throw that error on one form only, but work fine on others?</p>