Error Connecting to Undo Manager of Source File XYZ

Question

I've been getting an error recently while debugging an ASP.NET application in Visual Studio 2008:

'Error connecting to undo manager of source file XYZ'

Any idea how I can get rid of the error?

Answer 1

Even simpler:

My experiment consisted of simply opening the designer.cs file, typing a character somewhere in the file, deleting the new character, saving the file and recompiling.

Found on That One Developer Blog and it worked perfectly for me.