If you’re switching to the new Unity Input System and using Visual Studio code, you’ll probably hit the hiccup I did.
After switching back-ends, you’ll find that you’re not able to use the new namespace. If you try, you’ll get “namespace not found.”
To fix this, you’ll simply need to create the csproj file so VS Code knows to use the new assembly.
In Unity Editor go to Edit->Preferences
Choose “External Tools”
Click the “Regenerate project files” button
After that, VS Code should recognize the new UnityEngine.InputSystem namespace!