Publish Project Fails

Question

I get the following error when I attempt to publish my project:

Error   1   Copying file System.Net.Http.Formatting.dll to obj\Release\Package\PackageTmp\System.Net.Http.Formatting.dll failed. Could not find file 'System.Net.Http.Formatting.dll'.      0   0   Applications

A few points to consider.

• First, this solution has two projects, both reference this dll.
• Everything compiles and everything runs. (i.e. no missing dll's at
  run time).
• This dll and it's package exist in the packages directory for both projects, and all are the correct version.
• I've ensured that there are no references to the wrong version in any of the the web.config or app.config files.
• I have tried several different variations of updating, deleting and reloading all packages for both projects from nuget, and nuget package manager reports no updates at this time.
• This project has been published successfully many times before (most recently was 10 days ago)
• This is in Visual Studio 2013 with current updates

Any ideas on where to look?

(Update - I've also tried deleting and recreating my publish profile without success)

Answer 1

In my csproj file I had two spurious entries:

Content Include="System.Net.Http.Formatting.dll" 
Content Include="System.Net.Http.Formatting.xml" 

Deleting these entries fixed the problem with the publish. How or why these existed is a mystery of the sea.