Parts inside the character model influence the jump force

I’m able to reproduce this by starting a blank place file, spawning my character, inserting a big 50x50x50 unanchored part into the character model, and then jumping around near it. The character occasionally gets flung sideways.

This is a new issue in a game of mine where I’m storing models inside the character. The models have lots of parts, so not only do you get flung when you jump, it also lags whenever you jump while it calculates the force.

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Yes, i’m having this same issue with vehicles in my game. When a user jumps out it’ll lag a little bit, then fling them. However I didn’t know it was caused by parts being inside the character model. Thanks for sharing that!

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I imagine this is the due to the nature of how Humanoids calculate physics… I would personally consider storing any parts or models in the player’s character model bad practice, anyways.

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This is a new behavior. Putting things inside the character has been a historic method of ensuring things get cleaned up when the player leaves. There’s no real reason to believe that it’s somehow wrong, the character is just a container. The unwanted behavior relates to the humanoid.

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This keeps causing people to get flung around in my suspension test because cars aren’t weightless. Makes it very difficult to enter other cars. This has been an issue for a long time in my experience and any game that parents something like a car to your character (just see Brick Cars) has these flinging issues.

I hope this gets fixed soon.

just noticed that this is still an issue and that I already reported it. want to make sure that somebody knows about it. things inside the character that aren’t attached to the character make the humanoid jump wrong.

Yeah, I’ve dealt with this many times. I’ve had to create scripts that manually create things when you spawn and destroy them when you die, all because putting them inside the Humanoid messes things up.

I can confirm this bug still is happening.
To reproduce simply make a script that creates a new part, parents it to the player and then jump near the part a few times. (CanCollide = true, Anchored = false)
https://gyazo.com/d18f3cbc88f2916b95a7bff58c62d4d3
Hopefully it will get fixed soon.

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This has also happened to me. It is still an active bug.

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It is still happening, still haven’t been fixed yet. I find this a bit irritating in games, so it’s still an active bug for sure.

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Could you try enabling the Massless property under the part? Another solution could be reducing the parts Density to minimum (0.01), if the characters mass as a whole contributes to the jump force then that could be the cause, theoretically it would still add really small force (with minimal density) but hopefully the effects are small enough to work as a temporary fix (or too small to affect velocity)

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Still happening to me as well, why should I waste server resources when I could just insert stuff in the character’s model without having to add script checks?

Seems to have resolved the issue for me, but I’m still quite lost about this being left in the dark.

Yeah this issue is really gettin me stressed out rn, super annoying. Found nothing on how to solve this problem

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Bumping this because the bug still exists and I’d like to see some sort of follow-up.

I’ve reproduced this by spawning a part 20 studs up, setting the parent to the character, and setting the network owner to the player.


The strange jump force influence now only happens for a short moment after the part hits the ground. It will not happen if the parts network owner is set to the server.

I’ll attach the .rbxl file here incase anyone needs it:
jumpbugrepro.rbxl (54.0 KB)

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this seems to be occuring in my game as well - a mysterious force that pushes players in one direction when they jump

Not sure if anyone is still having issues with this, but it can be solved by making all the parts stored in the character massless and non-collidable. Also make sure there are no forces pulling on any of the parts.

making anything near the character non-collidable is a workaround, but definitely not a proper solution and not always practical. The real solution is to fix the conditions that determine when these mysterious push forces are applied to the player.

Surprisingly, today I also found this bug also happens even if the nearby part’s collisiongroup make it non collidable with the player - another oversight in this hidden ‘push’ code - I was able to reproduce a situation where if a part is welded to the player, it will still exert a pushing force on your player (seemingly in an effort to get space away from the attached object) as long as ‘cancollide’ is enabled on the welded part, despite the collisiongroup of the part is non collidable w/ the player. As soon as you uncheck ‘cancollide’ for the welded part the push force stops.

another aspect of this bug: I believe I root caused characters getting pushed in my game:

When players equip the heavy armor in my game it has a helmet- any existing hair of the player is removed and a copy of their hair/hat is stored temporarily in a folder under the character, to be re-added if they switch back to an armor with no helmet. I observed that the handle for this hair/hat’s is often ‘cancollide = true’. I suspect due to a bug in this under the hood ‘push to separate code’ that is in the roblox engine, roblox seems to occassionally think you may be colliding with a nearby object (in this case, your removed hat/hair) even though it is not something that you would get stuck inside, or need separation from, and is merely dormant in a folder under the character.

As a temporary workaround I’m setting the handle of any removed hat/hair to cancollide = false. Yet to confirm this will stop this annoying bug in my game, but I believe that is what is happening for my particular experience with this issue.

Couldn’t this easily be fixed by fiddling with CustomPhysicalProperties & making the parented part massless?

And even what I said was false, I feel like the solution doesn’t have to require elaborate/complex code. Unlike tab glitching, which nothing you do in studio can patch it without false positives/downsides.