title: session_start() causing empty $_POST after form submission
body: <p>I am testing my page which has a very simple form:</p>
  
  <pre><code>&lt;form action="script/check.php" method = "post"&gt;
      &lt;input type = "text" name = "email"&gt;
      &lt;input type = "submit"&gt;
  &lt;/form&gt;
  </code></pre>
  
  <p>When my <code>check.php</code> file has the following code, it works fine:</p>
  
  <pre><code>&lt;? 
  var_dump($_POST);
  ?&gt;
  </code></pre>
  
  <p>The output is <code>array(1) { ["email"]=&gt; string(5) "hello" }</code>, as expected.</p>
  
  <p>When <code>check.php</code> includes <code>session_start()</code>, <code>$_POST</code> becomes empty.</p>
  
  <pre><code>&lt;?
  session_start();
  var_dump($_POST);
  ?&gt;
  </code></pre>
  
  <p>The output is now <code>array(0) { }</code>.</p>
  
  <p>It's difficult to search for this problem, unfortunately most of the results I find online with these search terms are about empty <code>$_SESSION</code> variables, which is not a problem for me. The problem is <code>$_POST</code> is empty.</p>
  
  <p>There is a catch: <code>$_POST</code> goes through correctly when I test the page from a local machine, on the network where the server is stored. For everywhere else, this is not the case, the site is unworkable. This is extremely odd as I've been using scripts of this type for months without any problem, and outside users have been able to connect without issue. I'm thinking it's a directory permission problem, but I can't be sure without more information.</p>