Prefabs broken in 4.6b20

Very weird problem here, and I wonder if anyone else met this situation with 4.6b20.

After I installed beta 20 (from beta 19) Unity started displaying the "Lose Prefab Connection" warning window every time I deleted a prefab from a scene. Not an object inside a prefab mind you, but simply a normal root prefab.

And when I was dragging a prefab from the project into the scene it was white, not blue! It felt as if Unity's prefab/normal object detection was inverted.

I also noticed that when I wanted to open a scene using the menu Files->Open it didn't work. Yep the "Open Scene" was broken. Only when I double-clicked on the scene file in Windows explorer did Unity launch with the scene. And then the Open Scene menu was working again.

Basically Unity was more or less broken and I thought ok, I'm simply going to delete the Meta folder in the project and let Unity rebuild the connections. Which it did, except after that ALL THE UI COMPONENTS were missing from Unity: the Add Component->UI menu was completely empty!

I thought oh my god my project has exploded! Except that I reinstalled beta 19 and everything is fine again. So in my experience beta 20 has some very, very serious problems. But I was wondering if anyone else had the same kind of issues...

 

I'm definitely getting the "lose prefab connection" warning every time I delete a prefab from the scene.

 

Yep. There is definitely something afoot here.

 

I'm getting the lose connection dialogue as well

 

Yup. Whenever I try to delete anything in hierarchy, I get the warning.

 

Thanks for the heads up! It makes sense; this seems related to the fundamental way prefabs are working, which is beyond the scope of the mere UI module at this point.

Beta 20 (of 4.6) simply inherited from the latest update in the 4.5 branch. I suspect this issue is related to preliminary work for nested prefabs. It is surprising that nobody caught the issue before release.

 

I'm still getting this in 4.6.1f1.