IIS wincache failing

Question

This is driving us all nuts.

We have an IIS web server running php using wincache.

In iis we have the document root and a second part of the website mapped using a virtual directory.

First, here is the error:

PHP Fatal error:  session_start(): Failed to initialize storage module: wincache (path: C:\Windows\Temp)

We got the error to duplicate in a simple 1 line php file:

<?php
session_start();
?>

Here's the kicker

This file throws NO errors if placed anywhere in the root doc folder. BUT once placed in the virtual directory it will work for about 5 min then fail. It will continue to fail until we restart IIS.

We also have 2 servers identically configured. It's working with no issues on of the 2 servers.

Answer 1

It sounds like the IIS application pool ID under which PHP is running does not have permissions to write to C:\Windows\Temp. You should check the ACLs on the folder to see if it is writeable by your app pool identity.

c:\Windows>icacls Temp
Temp NT AUTHORITY\SYSTEM:(OI)(CI)(S,RD)
     BUILTIN\IIS_IUSRS:(OI)(CI)(S,RD)
     BUILTIN\Users:(CI)(S,WD,AD,X)
     BUILTIN\Administrators:(F)
     BUILTIN\Administrators:(OI)(CI)(IO)(F)
     NT AUTHORITY\SYSTEM:(F)
     NT AUTHORITY\SYSTEM:(OI)(CI)(IO)(F)
     CREATOR OWNER:(OI)(CI)(IO)(F)

If you don't see BUILTIN\IIS_IUSRS on the ACL, then the default app pool ID can't write to that directory. If you're using a custom user ID for the app pool, you'll need to make sure it's on the ACL for the folder.

Answer 2

Not exactly the answer I was looking for. But we just spend a couple hours switching to Apache. Bug is gone, server is faster, all is good.