All my main development machines are now running Visual Studio 2012.  I have a few new projects in VS2012 and have begun updating my old projects to it as well.  I ran into an annoying issue today that I need to post.

My Blog by Email site was built using VS2010 and ASP.NET MVC 3.  My new machine, which I am working on right now, is running Windows 8 and VS2012.  Recently a new user started using the site and discovered a few bugs I needed to get fixed.  I cloned the repo from Bitbucket and opened the solution in VS2012.

My first tip-off that there was an issue is when the Migration Report displayed 7 errors all on the _bin_deployableAssemblies\ folder.

BlogByEmail\_bin_deployableAssemblies\Microsoft.Web.Infrastructure.dll: Failed to backup file as C:\vsp2k12\BlogByEmail\Backup\BlogByEmail\_bin_deployableAssemblies\Microsoft.Web.Infrastructure.dll 
BlogByEmail\_bin_deployableAssemblies\System.Web.WebPages.Razor.dll: Failed to backup file as C:\vsp2k12\BlogByEmail\Backup\BlogByEmail\_bin_deployableAssemblies\System.Web.WebPages.Razor.dll  (... Plus 5 more files)

My second is when I went to run the project and the build failed for the same 7 files.

If you recall the _bin_deployeableAssemblies folder is used to aid in bin deploying MVC 3 applications to [shared] hosts which don’t have ASP.NET MVC 3 loaded.  You can read more about it here [@haacked.com].

It turns out this isn’t required in VS2012 as I found here :

Starting with MVC 3 Tools Update we are now using Nuget package references, which means that your project is automatically bin-deployable. Since the tooling gesture is no longer necessary it was removed from VS 11.

The fix here is really simple.  Remove the files and _bin_deployableAssemblies folder from your project.  Everything should compile just fine.

Now the one part I have not figured out is where or how we get the files that used to be in _bin_deployableAssemblies.  I don’t see them in the bin folder as I assumed they would be.  I will need to do some test deployments at my host, Arvixe (I think they didn’t have MVC 3 loaded).  Add a comment below if you h ave some knowledge around this.