If you encounter this error in your ASP.NET application after updating it while using NServiceBus:

Server Error in '/' Application.
Type DataPump.Infrastructure.Messages.MyMessage was not registered in the serializer. Check that it appears in the list of configured assemblies/types to scan.
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Exception Details: System.InvalidOperationException: Type DataPump.Infrastructure.Messages.MyMessage was not registered in the serializer. Check that it appears in the list of configured assemblies/types to scan.

you can most likely clear it by deleting the Temporary ASP.NET Files, which you’ll find in your c:\Windows\Microsoft.NET\Framework(64)\{version}\ folder.

You may need to stop your w3svc process for the site in question in order to unlock the files.