Visual Studio 11 complains about one namespace import in web.config

Question

I have a .NET 4.0 web site which was coded in Visual Studio 2010.

I installed the VS11 beta last night, and am using that to work on the web site today. I did NOT change the web site to be .NET 4.5, it is still 4.0.

I have a number of custom libraries which I've written, and use in most of my projects (db access, LINQ extensions, etc.). I have them all <system.web><pages><namespaces><add/>ed in the web.config of my project so that I don't need to put an Import line at the top of every file where I want to use things from them.

This all works fine and as expected in VS2010, and in VS11 it all works fine, ... EXCEPT for one single exception. ONE and ONLY one of my custom libraries, when I have it included in the web.config, the design-time compiler outputs an error message to the Error List window stating:

Error: The namespace 'MyLibraries.LIB' is not a valid identifier.

All my other libraries continue to work fine, just as they did in VS2010. I thought maybe there was an invisible character embedded in the file or something, so took out the whole <add/> line for that namespace and retyped it from scratch. No joy. I've also tried removing the DLL (and associated files) from the bin directory and re-adding them, also with no change.

Answer 1

Turns out this wasn't so much a problem with VS11 itself, but with the Framework 4.5.

I uninstalled VS11 and VS2010 still had the same problem. I then saw that uninsting VS11 did NOT uninstall .NET 4.5, so I uninstalled that, and then 2010 was good.