Unity lost reference without any changes to scene.unity

Unity lost all references in a scene. A scene no one ever touched since 15.07.2017. There is a single log related to this *.unity file and that was when the file was added to the repository on 15.07.2017

However. This scene lost many references to gameobjects in this scene, and is therefore suddenly completly broken.
101040-unitylostreference.png

This happened to me to, seemingly out of nowhere - all I’d done is modify some existing scripts in my project. I was also getting errors about dll’s not found that hadn’t been moved. I’m using git so could go back, but I found that after closing and opening the project 3 times, all the weird errors went away and the object refs reappeared. Not satisfying, but problem avoided for now!

The scene itself doesn’t have to change for that to happen. In fact, the most common reason is that the prefabs it’s referencing were moved or changed to such a degree that it can’t find them anymore. Did you do a refactor on how you organize assets recently?

The same thing happened to me in the middle of a developer session.
Everything worked on a test. About an hour later after I called PLAY, all references were gone throughout the project.

I only adjusted the code for 3 existing scripts.
The first try was a Server Rebuild without any visible effect.
In my case, quitting and restarting Unity helped.

I found this thread because I wanted to make sure before any action that I would not destroy more than necessary.