grey screen Unity 5.4.2f2

When I open Unity I get a grey screen.
Do you have any ideas to solve this?

If you use only UI like me, the problem is that your canvas(es) are not attached to the camera, so :

  1. Select your canva (or all of them if you have many)

  2. In the inspector : Render mode → choose “Screen Space Camera”

  3. Drag and drop your camera (from the hierarchy) into the “Render Camera” Case (in the inspector)

It’s something that should be automatically fixed, but no… Have fun