The code editor says that you are missing an assembly reference and clearly you have the packages installed (UnityEngine.xr for instance).

[thefirstfloor]

The code editor says that you are missing an assembly reference and clearly you have the packages installed (UnityEngine.xr for instance).

[thefirstfloor]

Try the following solutions:

• Remove projects files.

  Exit Unity and your code editor and delete all .csproj and .sln files in the root of the project. Open Unity and your project, select Assets>Open C# project
  This will regenerate all projectfiles with current state of Unity’s settings.