Crash during physics replication


I keep getting a crash on the Promoted version of the engine (changelist 3932718). It appears to be something to do with physics replication and attachment. The game I’m working on has a whole inventory system with items that can be picked up, dropped and given to other players. The whole thing is multiplayer and the crash only happens when playing with multiple people. The crash happens more often when there are more people.

I have a screenshot of the crash in debugging mode as the logged version doesn’t give much of an insight into the problem:

I’ve looked at the code path shown above when the crash it not happening and as far as I’m aware, the variable OwnerComp has always been a class of UPrimitiveComponent (generally one called BodyMesh which is a UStaticMesh component). However, when the crash occurs the OwnerComp variable points towards a class of AActor, which contains a primitive component. I’m assuming this is not intended as the conditional variable set for OwnerComp calls for a UPrimitiveComponent class type.

Reproducing the bug in a new project would be difficult as I’m not exactly sure what is causing the crash. Although I manage to get it to happen more often when I run a multiplayer session with 5 players, each being given items for a few seconds, then dropping the items after another few seconds. While the players are doing this they are teleported randomly around the map.

I think this crash happens some time after an item has been dropped, based on the state of the OwnerComp actor that is referenced. So this should mean it is an item that has been dropped and is simulating physics. But I did notice it has a reference to a character in a AttachComponent variable but not the AttackParent variable.

If anyone could give me direction here it would be really appreciated. I’m really stuck on what to do here and not sure if this is an engine bug or something that I’m doing wrong.

I’ve attached a text file including the crash reports found from a development build. These logs were collected under real networking conditions, but the debugging above is under the editor DebugGame configuration.

[Crash Reports Download][2]



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