Recently i had some problems after uninstalling Visual Studio 2011 Beta, i found a solution for the previous version of Visual Studio but with the necessary replacements worked just fine for the newer version.
If you find out that after trying out one of the beta versions of the new Visual Studio 2011 and uninstalling it together with the .NET Framework 4.5 or uninstalling only .NET Framework 4.5, every time you try to load a project on Visual Studio 2010 you face the following error:
“Unable to read the project file ‘Project.proj’.
MSBuildToolsPath is not specified for the ToolsVersion “4.5” defined at “HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\MSBuild\ToolsVersions\4.5”, or the value specified evaluates to the empty string.”

This might be caused by the Windows SDK still present on the machine or at least some of the registry keys it uses. To fix this issue you need to do the following:
- Make sure Visual Studio 2010 is completely uninstalled (go to “Control Panel -> Programs -> Programs and features” and make sure it is not listed
- Make sure the following registry keys do not exist in the machine:HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\MSBuild\4.5HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\MSBuild\ToolsVersion\4.5If you are working on a 64bit OS you will need to delete them from the 32 bit part of the registry. To accomplish that click “Start Menu -> Run…” and type the following command:%WinDir%\SysWOW64\regedit.exe
This workaround was taken from MSDN blog, check out the original version at:
Original article at MSDN blogs »











