While developing a web application for a friend of mine, I ran into a Visual Studio error message I hadn’t seen before: Error connecting to undo manager of source file ‘D:DevelopmentSomeWeb ApplicationDefault.master.designer.cs’.
The error occured whenever I tried to start the (web) application in debug mode. The application did start OK after the error message though. Starting the application without debugging didn’t cause the error.
I closed the solution file I had opened, but that didn’t solve the issue. Stopping the ASP.NET Development Server didn’t do anything either. I had to exit Visual Studio al together to get this error to go away.
I searched for this specific error, and saw it already occured in Visual Studio 2005 SP1. Scott Hanselman has a blog post on how he solved this issue. Now, in Visual Studio 2008, this error still seems to be in there…
Hello,
here you can find a very simple solution:
http://social.msdn.microsoft.com/Forums/en-US/csharpide/thread/79e84cfe-3d4b-43c7-8d86-723208e4a64c/
From that post:
“This happens only occasionally when making changes to the aspx file, and then hitting F5 for ‘Start Debugging’. If I manually modify the the designer.cs file in question (just add a space somewhere), save it, and go, the problem disappears.”
I tried it and it works!!