BestChat.Prefs.GUI.Ctrls.csproj which references the DLL project BestChat.Prefs.Data. I'm getting the error shown below:BestChat.Prefs.GUI.Ctrls.csproj is <ProjectReference Include="..\BestChat.Prefs.Data\BestChat.Prefs.Data.csproj" />. BestChat.Prefs.Data is one directory up. So the relative path should be correct.