PHP - Large POST Request Server Error
<p>For my Webserver I'm using IIS8 on a Windows Server 2012 with ASP.NET, PHP7+ and FastCGI.</p>

<p>My problem: When I try to submit a formular (HTML to PHP) with a value string, in thic case longer than 20.000 characters, the server returns a 500 Server Error <strong>OR</strong> it doesn't recognize the post request at all. </p>

<p>My HTML/PHP Code: </p>

<pre class="lang-html prettyprint-override"><code>&lt;?php if(isset($_POST['submit'])) { echo "Got it!"; } ?&gt; 

&lt;form action="" method="post"&gt;
&lt;input type="text" value="String with 20000+ characters" name="value"&gt;
&lt;input type="submit" name="submit"&gt;
&lt;/form&gt;
</code></pre>

<p>By clicking submit the server error comes up. Within the post request these lines are inserted in the PHP Error Log File: </p>

<pre class="lang-html prettyprint-override"><code>[] PHP Warning:  Unknown: Unable to create temporary file, Check permissions in temporary files directory. in Unknown on line 0
[] PHP Warning:  Unknown: POST data can't be buffered; all data discarded in Unknown on line 0
</code></pre>

<p>I also <strong>edited all configuration options</strong> that may be in connection with this. </p>

<p>php.ini</p>

<pre><code>post_max_size = 1024M
memory_limit = 512M
upload_max_filesize = 1024M
</code></pre>

<p>web.config on my server</p>

<pre><code>&lt;system.web&gt;&lt;httpRuntime maxRequestLength="1048576" executionTimeout="3600" /&gt;
&lt;/system.web&gt;

    &lt;security&gt;
&lt;requestFiltering&gt;
    &lt;requestLimits maxAllowedContentLength="1073741824" /&gt;
&lt;/requestFiltering&gt;
</code></pre>

<p></p>

<p>Thanks for any support. </p>