Here’s an interesting conundrum, and a solution. I selected to ‘upgrade’ the 3_Project_Boost during my following of the git course Cloning Remote Repos, all the various elements upgraded except for the Directional Lights which generate a non-compatibility error.
To fix the error, it seems to be necessary to go through each scene (Level), select the directional light in the Hierarchy, then call up the Lighting window (Menu: Window | General | Lighting) and click on Generate Lighting at the bottom of the Scene tab. Note that it may be necessary to untick Auto Generate before it’ll let you click on the Generate Lighting button—for consistency retick the box if you had to untick it.
I’m rubbish at this type of game so I could only test it through level 1 and then die.