Starting today I’ve been getting strange reports of people crashing directly after interacting with conveyors in my game. I tried it myself and there does seem to be a crashing issue which I could reproduce about 100% of the time by enabling/disabling the conveyor a few times.
UPDATE: This seems to happen from the tweaking of the velocity property of the conveyor and not the use of a legacy BodyPosition which I thought first. I have set up a repro place that simply switches an anchored part between Velocity (0,0,0) and (0,0,-10) with a car on top. This produces the crash 100% of the time for me as long as I wake the physics sleep when the conveyor starts. Sometimes happens straight away and sometimes after it has stopped and started a few times. ConveyorCrash.rbxl (74.4 KB)
The crash happens both in studio and in-game. It either freezes permanently or gives me the error message in the video, but only if there’s a car on the conveyor to run the above code on. Not sure if it’s the whole server that crashes or just the client.
Even if it used to work, you should never use infinite values in physics objects. This is very likely to cause future problems even if we fix whatever change in behavior triggered this specific problem.
After converting the old BodyPosition code to use constraints, and even disabling the physics wake code altogether I was still getting the issue so it wasn’t related to BodyPositions as I thought first. The issue seems to be just from editing the velocity of the conveyor with a car on top. I’ve updated the thread with a repro place.
I also filed a report similar to this which has not been approved yet. We don’t use any constraints and we are recording the same issue with the server immediately crashing when the conveyers hit a velocity of 0.
@Panwellz I’m unable to repro this crash in Studio using your place. What do you mean by “as long as I wake the physics sleep when the conveyor starts”? What method do you use?
My issue was similar but it only happened in game but not studio. Your code change appears to have fixed the issue for some fellow devs that I know as well.
It’s just that the car in the repro is supposed to start and stop every 5 seconds, but it doesn’t restart after stopping unless you touch it due to the physics falling asleep. For the crash to happen you might need to wake it every time.
The feature that was disabled earlier fixed it so I’ll mark this solved