If you are getting following error:
Could not load type ‘System.Web.UI.ScriptReferenceBase’ from assembly ‘System.Web.Extensions, Version=188.8.131.52,
Then you are on the right article
It’s highly likely that you compiled your code using .NET 3.5 Service Pack 1 but deployed to a system that has .NET 3.5 without Service Pack 1.
ScriptReferenceBase is a new class for Service Pack 1, clearly a refactoring of ScriptReference to allow common code for the new CompositeScriptReference class. If you compile your code using SP1, you will include a reference to this class, which does not exist in .NET 3.5 pre-SP1. When the non-SP1 runtime tries to load the class, you will receive the exception above.
- Compile using .NET 3.5 without SP1.
- Install SP1 on the target system