Problem
Unable to access VSA Login page with error message:
Server Error in '/vsaPres' Application.
Could not load type 'System.Runtime.CompilerServices.ExtensionAttribute' from assembly 'mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089'.
Cause
The server is running an older .NET version. ASP.NET is looking for a file that does not exist. The reason being the file is part of the newer .NET version - .NET 4.5.
Solution
1) To run Windows Update and install all Pending Updates
OR
2) Install .NET 4.5 manually using the following link: https://www.microsoft.com/en-gb/download/details.aspx?id=30653
Applies to
Kaseya VSA - All versions