CRITICAL COLLISION ISSUE! collision between blocks and terrain is always disabled since latest update!

I have noticed people their creations sinking through the ground in many weird ways since the last 3 hours.

I went away for about 3 hours, came back and noticed 20 private messages of people sinking through the ground.

I think the collision fix that was pushed out 3 hours ago could be the cause for this.

This issue is happening to anyone playing my game as of now, so this is an extremely critical issue.
Can this fix get reverted as soon as possible?

The collision between the aircraft and terrain is completely disabled except for the player.





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Has this server been running since before that announcement? It’s not uncommon for servers to live much longer than a few hours. If you haven’t already you may need to Shut Down All Servers on the game for this to take effect.

If you’ve already done that let us know and link us to the game so we can reproduce and investigate!

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The server seems to be running for 31 hours already, but the issue is 100% easily reproducable in studio.
I haven’t received messages about this before 3 hours ago, it all came within a huge wave of private messages within the last 3 hours.

repro.rbxl (27.2 KB)
Launch a test server and the red part will fall right through everything.

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Sorry i totally forgot about the link, here it is!

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I have noticed the issue is not active in a VIP server anymore now.

However though the issue is still active in live servers.

Do you want me to shut the servers down?

Players playing my game need atleast 100 seconds to save their data to prevent data loss ingame, so i can only shutdown my game via my method.

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Based on the repro you provided, this only happens when a CollisionGroupID is set for a CollisionGroup that doesn’t exist yet (uninitialized).

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In that case, i dont know what is causing it.

The issue is still live in the public servers, so you can repro it by placing a few blocks with a rocket engine behind it, placing a main pilot seat, launching the aircraft and then hold r to make it go forward and see it fall through the ground.

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Is it possible that objects that are building blocks in this game have non-zero CollisionGroupIDs?

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Doesn’t the game automatically set the blocks to a collisiongroupID when you set the parts to a collisiongroup?

I can see the parts having a nonzero collisiongroupID, but i dont think i have actually set them manually, i use the normal code for setting the parts to a collisiongroup.

PhysicsService:SetPartCollisionGroup(Part, "Plane " .. Player.Name)
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But the difference is whether or not CollisionGroupID 12 actually exists or not. This bug seems to happen when GollisionGroupID of a part is set to an ID of a group that doesn’t exist.

Like maybe CollisionGroupID 12 existed in a different game and was copied over here where CollisionGroupID 12 doesn’t exist.

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For each player a collisiongroupID is created for both the player and aircraft.

The player collision group disables the collision between the walls around the build area of the buildingzones.
The aircraft collision group allows for the possibility to disable the aircraft to aircraft collision when a player is blacklisted.

it cant be possible that every single collisiongroup does not exist while the player collisiongroup is working just fine.
If the aircraft collisiongroup would be missing, the player collisiongroup would be missing aswell and that means people could not exit their own buildingzones, which did not happen.

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I have just joined someone his VIP server and noticed it doesn’t happen to terrain only.


There are no errors in the server logs and client logs.

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I’m going to roll the flag back and investigate.

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I have printed the existing collisiongroupID’s in a broken server and the groups seem to exist as intended.

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When are the groups created?

Are they created during the spawn process for the Planes?

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It is definitely because of the collision fix.
I was experimenting a bit more and eventually fell through the map aswell.

I was sinking through the ground and out of nowhere my aircraft popped right back to the service. (probably when you disabled the fix)
It seems to be working correctly again now in the same server i was in.

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The collisiongroups are created as soon as the player joins the server.

Here’s an example of what the collisiongroups look like.

PhysicsService:CreateCollisionGroup("Plane " .. Player.Name)
PhysicsService:CreateCollisionGroup(Player.Name)
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What collision group is the Terrain set to? Default?

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I dont change anything about the terrain collisionwise.

The collision issue also seemed to appear with regular parts at a later point.

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We’ve seen a collision related issue that could be connected that started (I think) with the release of 480. We see the character as being able to jump partly into another part and then they get thrown out of the part sideways. You can see it in this video where I’m jumping at the top of a cube and just missing the top:


This is a brand new project with just that cube added to the place. There’s no scripts added. I’m not pressing anything when I hit the top of the cube.

We’re also seeing this live in our game. You can see it about 2 seconds into this video:

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