Web.config transformation: Unrecognized attribute 'xmlns:xdt'. Note that attribute names are case-sensitive

Question

I\'m getting this strange intermitent bug in a MVC 3.0 project When I build the project sometimes I get the following error message:

Unrecognized attr

Answer 1

I've also run into this issue. For me it was caused by my having created a new debug configuration called, "DevDebug". I fixed it by making a copy the web.debug.config, named web.DevDebug.config and added it to the project.

Then, when I attempted to run the aspnet compiler, it was satisfied that it could find the right configuration version of the config file to merge in.