The trouble with 500 internal service errors is there're so hard to debug. What's more annoying is there are probably 500 different ways to fix a 500 internal service error. At least the search results tend to lead you down dead ends. Well – I was getting a 500 IIS error today on all my SharePoint sites, including central administration, and since my fix felt somewhat unique I figured I'd post it. However, this post will probably be a drop in the ocean of search results, so I doubt anyone will notice… but you never know! Sorry if this is another "dead end" J.
So – things were great in my farm. Had a few web applications, site collections, central administration, etc. Then I got the idea to install a third party app (Site Minder) onto the server that ran on IIS. I installed the 32 bit version of the product and since my server is a 64 bit server, it configured IIS to run in 32 bit emulated mode (stupid idea – I know). Well, MOSS x64 version doesn't like when you do that, and all of a sudden all my sites started returning 500 errors.
To fix the problem I uninstalled the third party and turned off 32 bit emulation mode by running this command at the command prompt:
CScript "%SystemDrive%\InetPub\AdminScripts\adsutil.vbs" set w3svc/AppPools/Enable32bitAppOnWin64 0
So there you have it – another needle in the haystack of 500 IIS error fixes. Good luck!
Phil