Since I got a new computer (or rather an old one repaired), I first installed IIS switched the DefaultAppPool to .NET Framework Version 4.0 and deployed Orchard from my solution.
When I then open Orchard in my browser, all I got is a white page. Looking at the IIS log files shows that an internal server error:
2014-02-07 10:26:48 127.0.0.1 GET /orchard – 80 – 127.0.0.1 Mozilla/5.0+(Windows+NT+6.1;+WOW64;+rv:27.0)+Gecko/20100101+Firefox/27.0 500 19 33 1
This unfortunately didn’t help much. Then I remember that I already once had a similar and had to use the ASP.NET IIS Registration Tool to install the version of ASP.NET and register ASP.NET in IIS by executing the following in a DOS prompt:
cd C:\Windows\Microsoft.NET\Framework64\v4.0.30319 aspnet_regiis.exe -i
After doing this and setting the rights for the DefaultAppPool user again so that Orchard can write to the App_Data directory, my Orchard Installation was working fine.
It’s just a pity that there is not a clear error message written to the log file in such cases…