After migrating servers today, one site keeps getting the error above. A quick search on Google showed that it's a fairly common problem, and there are lots of fixes, so far I tried the following:
1. %windir%\Microsoft.NET\Framework64\v4.0.30319\aspnet_regiis.exe –i
This seems to be the most common solution, however it didn't work for me. I tried running the same from v2.0.50727, just in case, and from Framework folder, even though this is 64-bit version of Windows. Didn't work.
2. %windir%\Microsoft.NET\Framework64\v4.0.30319\SetupCache\Client\setup.exe /repair /x86 /x64 /ia64 /parameterfolder Client /norestart
I repaired the framework but with no results, I still get the same error.
3. Adding <add name="ManagedEngine64" image="%windir%\Microsoft.NET\Framework64\v2.0.50727\webengine.dll" preCondition="integratedMode,runtimeVersionv2.0,bitness64" /> to applicationHost.config, mine was actually completely empty - but that didn't help either.
The weird thing is that we have a number of sites running, all of them .NET4 and all working correctly - this is the only one running on v2 and it seems to me that it's the root of the trouble.
Short of re-installing the IIS, can you think of any better options? I'd rather not cause disruption to the service of the other sites.