Sudden change of bodymover physics when interacting with people's characters

Since yesterday (March 8th), there has been a sudden, dramatic increase of physics glitches in my ship game. Ships are flung in random directions when other players board them. It seems to happen especially when the player who boards the ship isn’t its network owner. Here’s a video that shows the problem. The bug happens constantly for the majority of my players that carry one or more people on their ships. This change is not caused by me, as I wasn’t editing the physical behaviour of my ships recently, so it must be caused by a Roblox update. It is a different issue than the BodyGyro bug that was already reported and fixed a few days ago.

My ships use bodymovers for movement: BodyPosition to stay afloat, BodyGyros to prevent flipping, BodyVelocity to go ahead and BodyAngularVelocity to turn. The player who drives a ship is set manually as its network owner, until a different player starts to drive it. The normal expected behaviour means that there is no sudden flinging when people board a ship (at least this is how it worked until yesterday).

In order to reproduce this bug, you can check out my game and board someone else’s ship. I can DM a file with one of my ships if it’s necessary.

A possibly useful information for fixing it is that it only seems to happen if the ship is boarded by a person who isn’t its network owner. The flinging is more severe if the ship is moving while being boarded. My guess is that the boarding player is now locally simulated as an infinitely (or at least very) massive object by the ship’s network owner, which results in the glitches I described.
Another interesting fact is that in the linked video, the ship got flung after the player that was standing on it respawned his character, causing his body parts to fall on the ship and glitch it.


If you could DM me one of the ships in a file. How hard would it be to make them work outside of your game?

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I’m so glad someone finally posted about this; I have been having the same exact issue, except in my hockey game. However,

I cannot say the same. BodyMovers overall act strangely, whether I have network ownership over the puck or not.

I have created a post with more information here:

If you would like me to also provide a repro place for you to test out the BodyMover issues in, I will gladly prepare one for you. Also, I believe you must test the repro place in an actual ROBLOX game; you cannot reproduce this bug in ROBLOX Studio. (not sure if that applies to his ship game as well or only to my hockey game)

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I am no ROBLOX Engineer, but it seems to be DIRECTLY related to this update. I tested my game on the Windows 10 version from the Microsoft Store (which you explicitly stated wasn’t updated) and the BodyMovers work normally, but when testing on the normal Windows player, the BodyMovers stop working correctly.

I’ve rolled back the update to collision detection. There were enough incidents reported to where I have data to verify locally myself, but I don’t want to cause service interruption.

Apologies for the issues.


Thanks! I have confirmed it’s no longer happening in my game.

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I have not tested the game myself but what my players are telling me is that the issue is fixed. Thank you so much for your help!

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Is there a way you could provide me with a small mockup of how your puck handling/physics work? I would like to test this an in isolated environment so that I can fix it without negatively impacting other players.


Yes, I can DM you with a place file if that helps.

That would be great! Thank you!

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