if you encounter the problem as follows:
<PathToyourDBFile> cannot be opened because its project type (.dbproj) is not supported by this version of the application. To open it, please use a version that supports this type of project.
..then you might have a problem with the registration of your dbproj extension (Team database edition projects). If a restart does not fix the problem, you can use the following command to start Visual Studio:
The issue is based on the problem that the Package has been marked as not valid and will be skipped during the start of Visual Studio, making it impossible to identity the type of assembly to use for reading and understanding the project file. Using the command will force Visual Studio to reload the package anyway.