Telerik: this specific issue is due to how Visual Studio loads the test project in which there are excluded old tests with errors in them. In Test Studio standalone, there are excluded files with code that has compilation errors (old tests that are no longer used and their elements have changed, so can not be found) and Test Studio takes those excluded files into account and does not use them for compilation (to see excluded files open Settings.aiis file with text editor and search for 'Excluded' keyword). In Visual Studio, the MS VS project file does not exclude those old tests and loads them into the project, which causes the compilation error afterwards. Workaround is either to delete the excluded files from Visual Studio, or exclude the same files from MS VS project options (https://msdn.microsoft.com/en-us/library/0ebzhwsk(v=vs.90).aspx).