Visual Studio 2012 C++ solution cannot be built after project import
I use Visual Studio 2012 Premium (Version 11.0.61219.00 Update 5). There is a C++ solution with some projects. Everything can be built without errors. Then I import a new (but already existing) project into this solution (via right-click -> Add -> Existing Project...). If I now try to build this project or any other of the previous projects, an error message appears: "Cannot perform requested action because a build is already in project" (which is not true, there is no build running).
If I try to rebuild the complete solution, another message is shown: "The operation could not be completed. Wrong parameter."
At the same time, there are no errors or warnings in the output view at all. Rather a build summary is given, which looks OK.
Build Summary
-------------
Total build time: 00:12.379
========== Rebuild All: 0 succeeded or up-to-date, 0 failed, 12 skipped, Completed at 30.09.2015 17:15:58 ==========
What could be wrong here? The project seems to be intact, I can open and view the properties, nothing suspicious. In fact, I imported the other 11 projects in the same way and from the same origin. Where can I get some Visual Studio log files or turn on any extended diagnostics which could point me to the right direction? Help me, I'm stuck!
We now figured out what was the reason for this behavior. The "guilty" project contained references to other projects in the solution. Other projects did, too (and worked); but the project GUID of this particular reference was not consistent with the actual GUID of the referenced project. If we view the contents of *.vcxproj file in a text editor, we find this GUID as nested <Project> element within <ProjectReference> element (s. screenshot).
As I mentioned in the comments, all projects were generated from an external specification written in a domain-specific language. There was a subtle bug in the generator mechanism, which under certain conditions led to this wrong GUID reference.
What amazes me, however, is that Visual Studio has not shown any easy-to-understand error message for such an obvious issue! If the path to the reference project is incorrect, the Studio points this out by a bold excamation mark (s. screenshot). Why not do the same in case of an invalid GUID? It took us several hours to diagnose this trifle.
