Client Desync with Physics Replication

Following up from: Physics on the Server Sometimes Desync Replication as the issue has started happening more commonly now.

Visual Aids:
Deepwoken

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Grand Piece Online

Details:
We don’t have any reproduction files but all the reports so far have been on Windows, happens across multiple different experiences. We’ve received reports in other experiences besides the two listed above but don’t have clips of it happening.
Both experiences have workspace.NextGenerationReplication not enabled. Both experiences have ImprovedPhysicsReplication set to Default/Enabled, we just set one to Disabled and plan to see if players stop reporting the issue.

Expected behavior

Client physics shouldn’t ever desync.

2 Likes

I am experiencing the exact same issue in my roblox game aswell

user report: Watch MedalTVRoblox20260618142209743 | Streamable

Hi, Thanks for reporting this issue. Please keep us posted about whether setting ImprovedPhysicsReplication to Disabled changes anything.

We haven’t received any further reports in the game we set ImprovedPhysicsReplication to Disabled but it could be that players aren’t realizing their physics are desyncing/aren’t reporting the issue. It’s still occuring in Deepwoken and a few other experiences I work for as the property wasn’t touched, we’d prefer to not disable the new replication optimizations, especially if it’ll be unable to be disabled soon, any chance this could be looked into?

I’ve also seen a lot of players having this issue in a multitude of other games with fast paced combat or lots of character movement like dashing.

As OP said - turning off ImprovedPhysicsReplication & NextGenerationReplication fixed it but I noticed this happening in specific circumstances in live games prior to making these changes.

Backstretch Battles Remastered by @Saab93AeroXWD

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(You can see it real well over the first jump and if you focus on the trees/fencing around the track

RoStock Racing by myself

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(Really obvious in the corners)

Additionally it happens on mobile too in RoStock Racing

But it does not happen in my game DIRT Freeplay

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The difference between the games that have the issue & the game that does not have the issue is that Backstretch Battles & RoStock Racing are “server sided” cars & DIRT Freeplay is not.

Backstretch Battles & RoStock Racing use a simple script such as this to set all cars onto the server:

local seat = script.Parent

seat.Changed:Connect(function(prop)
	if prop == "Occupant" then
		seat:SetNetworkOwner(nil)
	end
end)

We’ll only remove the “Disabled” option once we’ve fixed all the known issues, so please feel free to disable it as long as the issue you are experiencing is known to us.

Speaking of character desync, we’ve seen some reports about that. Some of them talks about the avatar desync, the other ones talk about avatar jitter, we aren’t too sure if they are the same issue or not.

Do you have a repro file for this by any chance?

Thanks!

If it’s happening prior to ImprovedPhysicsReplication, then it’s probably not related to it. However, it’s possible that ImprovedPhysicsReplication made it worse.

We have seen some reports about desync/jittering caused by network ownership changes, and we are working on something to fix it. I wonder if you can make a repro file for this car issue that we can test it locally?

I only saw this stuttering start up last night (although I hadn’t played anything over the weekend so uncertain about when this all started - at the least I didn’t see these issues last Thursday)

This file has the issues with the least amount of additional fluff. It’s just the singular setnetworkowner(nil) script that sets off the issues.
physics replication issue repro.rbxl (365.5 KB)