[RESOLVED] .Net 4 Windows 2008 Server

We are in the prgress of migrating our main webserver from windows 2003 to 2008 and we need to install .Net 4.0 All has been complete and the isntallation has worked fine.

Whenever we change an app pool to .net4 (In iis) and try to view that site, we get a 500 error. However nothing appears in the event viewer, so no method of trying to work out what is causing the 500.

Can anyone advise what are the best steps to start debugging this?

I know when I changed from 2.0 on an app pool to 4.0 there were some lines in my App.Config that broke it.

No idea if that is the cause, but it might be a good place to start.

Managed to find the problem, all stemming from permissions. Viewing the site locally on the server proved the turning point.