Just spent over a day trying to work out why my old project going from 2020.3 to 2021.1 no longer worked with Visual Studio. It would not open the solution properly and would give me no options to regenerate the visual studio project in preferences > external tools. Yet if I start a new project in 2021.1 it allows me to use visual studio properly and the generate csproj option appears. I copied my problematic project and started deleting chunks at a time and trying to run the project until I narrowed it down to this new obviously required package for Visual Studio - com.unity.ide.visualstudio, which probably comes as no surprise to Unity devs, but how is everyone else meant to know this is now required? you'd think that given that the project has Visual Studio selected as the the external editor in an older project created pre-2021 that it would add this missing required package in. There's also zero mention to this in the upgrade guide https://docs.unity3d.com/2021.1/Documentation/Manual/UpgradeGuide20211.html I searched the forums for any mention to com.unity.ide.visualstudio package. How on earth would anyone know about this otherwise? where should I be looking in the future to find out these important changes?