Blender 3.0.1 Unstable with scenes

I recently tried to use scenes to help manage my rendering setups. My setup is has a daytime setup using a base scene as a background and then the rendering setups each using the daytime scene as their background. What I’m finding is that if I try to add more than 2 or 3 rendering setup scenes, Blender will crash after a short time (anywhere from 5-10 seconds to a minute or so), and then every time I try to open that file again, it will crash immediately. This is the case whether or not I saved the file after adding the scene and before the crash.

In most cases I have been able to recover by selecting the auto-saved file, however the last crash (which resulted from trying to change the camera in one of the existing scenes) has resulted in me not being able to open the current file, and the most recent autosave file is more than 3 hours old. It looks like I can recover my work by appending into a new blank file.

Is this expected when trying to use scenes? Are they experimental, or is there special care that needs to be taken when setting them up?

From what you’re saying, you’d better file a report to the bug tracker to developer blender site.

I’ll look into doing that. Unfortunately I don’t (as of now) have a reproduction case. At least not one that is less than 1.5 GB in size.

Have you checked if your RAM is simply filling up? Blender does not empty RAM when switching scenes and if you switch often enough it is bound to crash.

Thanks. I will check that. At least that gives me something to look at to try and reproduce the problem.

Do you know why that is the case? Is it a technical limitation of the tech stack, or a bug?

It appears to be a limitation that was introduced with 2.80. I filed a bug report recently and Sergey said that the feature which is necessary clear the memory is not implemented yet and needs to be designed properly.
So it seems that it will be tackled but has no trivial solution.

Edit: Here is the task in question:

Thanks for the info. Good to know. After asking, I realized I could look at the Blender repo and discovered it’s mostly written in C so not likely a tech stack issue.

I also just realized that doesn’t really explain why I can’t open the .blend file at all after a crash. i.e. I’ll sometimes create a new scene, assign background and camera, and everything looks fine, so I save, and then I try to do a render or some other operation, at which point Blender crashes and then I can never open that file again. But I can append from it in a new file.