So I saved my little trivial scene yesterday and I got this:

' WARNING : 3000 - Save: [1] objects were not saved normally
' WARNING : 3000 - -- [Scene_Root.Camera] was saved, but is disconnected from the scene. (Floating object)

Normally I ignore these warnings, but I didn’t like the idea of saving a scene with a disconnected camera. I remember when you were able to save scenes without a camera; you just couldn’t open them again.

My camera view was still working, so I checked it, and I had an extra camera (that I didn’t create).

Long story short, I saved the scene and it seemed ok after. The extra camera disappeared.

See also this post about WARNING 3000 Objects were not saved normally.