Q:

Getting mysterious build error after upgrading solution to Windows 8.1

I have used windows store apps 8.0 in my project and upgraded it to be 8.1. And also upgraded Visual Studio from 2012 to 2013.
First, I got an error that cannot use the Microsoft.VCLibs Version 11.0 and 12.0. So I removed the 11.0 version.
And then I got this errors:

I tried to find some information on the internet, but nothing.
Also when I double clicked on the error it doesn't bring me to the error's spot.
I have tried to do many things, and nothing helped, so I decided to write this post.
Can someone help me resolve this errors?
EDIT:
I am adding some more information, maybe this can lead to the problem:

Solved:
With the help of Hans Passant the errors have fixed. The problem was that I had this duplicate on my resource file:

I did it twice because one is for buttons (that has content), and one is for message dialogs on code behind.
In Visual Studio 2012 this code was working fine, but somehow, not in Visual Studio 2013.
I deleted the row of Cancel.Content and the errors disappeared and it works fine :)

A:

Here is somebody else with the same problem.
I'll just copy Caplan's guidance.  Look through the .resw file(s) in your project and look for a duplicated "Cancel" resource.  I should note that intentionally forcing a duplicate resource produced another message when I built the program on VS2013:

1>MakePri : error 0x80073b0f: Processing Resources with error: Duplicate Entry.
  1>MakePRI : error 0xdef00532: Conflicting values for resource 'Resources/String1'

Same message from either duplicating the resource in the same .resw file and by making a copy of the .resw file and adding it to the project.  So Caplan's explanation isn't exactly a slam-dunk.  I'd pay attention to other projects in your solution that might also have a resource named "Cancel".  A likely scenario when your solution has a dependency on VCLibs, that sounds like you are mixing C# and C++/CX.

