HTTP Error 500.19 - Internal Server Error
Description: The requested page cannot be accessed because the related configuration data for the page is invalid.
Error Code: 0x80070021
Module: IIS Web Core
This may happen when .NET is installed before the site was installed on IIS
locate the appropriate under C:\Windows\Microsoft.NET
Open command prompt and run the command:
Restart IIS by executing the command
The .NET pages should work now.