Thursday, June 2, 2011

Sitecore CMS 6.1 with IIS 7.5 - 500.0 - Internal Server Error Calling LoadLibraryEx on ISAPI filter

I recently restored a Sitecore 6.1 website from source control after a hard drive failure and got the following error when trying to start it up from IIS 7.5:

HTTP Error 500.0 - Internal Server Error
Calling LoadLibraryEx on ISAPI filter "C:\Windows\Microsoft.NET\Framework\v4.0.30319\aspnet_filter.dll" failed

The application pool was set to .NET Framework v2.0.50727 but the ISAPI filter mentioned above was configured. Removing the 4.0 aspnet_filter resolved the issue.