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  1. Minecraft (Bedrock codebase)
  2. MCPE-172503

Entity Collision & Hitboxes Would De-Sync In Multiplayer


    • Icon: Bug Bug
    • Resolution: Awaiting Response
    • None
    • 1.20.1 Hotfix, 1.20.12 Hotfix, 1.20.15 Hotfix, 1.20.40
    • Unconfirmed
    • Xbox

      Original Title: Entity Collision Will Not Match With Actual Entity

      Entity Collision And Hitboxes De-Sync Across Clients (Multiplayer)

      This issue affects Xbox One S and Xbox One players.

      All versions of this issue have been affected by research and by online play:

      • 1.19.51
      • 1.19.60
      • 1.19.62
      • 1.19.63
      • 1.19.70
      • 1.19.71
      • 1.19.72
      • 1.19.73
      • 1.19.80*
      • 1.19.81*
      • 1.19.83*
      • 1.20
      • 1.20.1
      • 1.20.14
      • 1.20.15
      • 1.20.20
      • 1.20.30
      • 1.20.40

      This issue is only apparent in multiplayer. If the Xbox One (S) player hosts the world, they do not experience lag issues.

      *These versions are not confirmed or do not contain any issues from what we've played out of those versions and seemed fine, but we thought it was possible.

      My friend (I'll refer to him as "Revemnt") and I play on my world that I host games on since he enjoys playing the mode. I play on the PlayStation 5. However, this affected him before I switched on my almost decade-old base PlayStation 4. My friend is an Xbox One S player, and we have tested in the world I use with other Xbox players, and it has only affected Xbox One S players and below, never the Xbox One X or Series consoles. We plan to see if it affects Xbox One X but with more pressure.

      Within my end, since I am the host, and my other friend's end (I'll refer to him as "Ace"), who plays on a PlayStation 4, we do not experience the issue that Revemnt experiences. He experiences that particles coming from mobs, depending on the command block usage, do not match with the actual entity. The particles moving is the actual mob moving forward with its player detection hitbox (which the players will take damage from), but the actual entity is following behind it. The longer the system lasts, the farther the entity and the hitbox are from each other. The player can still interact with the entity if it hits the physical mob, not the one containing the particle.

      We tested if the issue is TPS-based since that depends on CPU and RAM, and we concluded that the issue is not TPS-based and the server does not slow down, and mobs still generally act fine entirely. Everything ran at a consistent 20 TPS, even with Ace in the world Revemnt and I were testing one day, which didn't slow down for him, as I said. We assumed by then it only affected Xbox players since no other PS or PC players I've hosted had the issue.

      We experienced this initially while playing on the same map; nothing has changed regarding the mob used. When the mob has spawned, the particle issue arises and only stops once the mob is killed. The issue has varied results and can become inconsistent with how it appears. Mostly, it can appear with one of the mobs I spawn, and it can immediately happen, sometimes taking more or nothing will happen. This happened back in 1.19.51. Although, we think it could've happened earlier in 1.19.


      We did another test in my main game world. It had better results with Revemnt, so it was more robust. We did a TPS test to see if it was consistent with him. He stated that the TPS was completely fine, but his only initial lag was minor FPS lag due to particles, though the problem was still present. After testing with other Xbox players, the actual issue seemed only present with Xbox One and One S players. 


      We later tested if it would affect me with the same mob command setup, which it didn't in his island mode world and the main game world that he had early on during 1.19.40 and above, which presented no issues for me.


      Here are all of our findings:

      • This happens with mobs that have or show particles
      • This happens to mobs without particles (Found 1.20.40)
      • This happens on mobs with effects on them
      • This happens to mobs with ANY command setup, regardless of type or family target selector.
      • We probably think it could be a RAM issue with Minecraft on Xbox One S and Xbox One, but we cannot put that into theory since it usually connects with the server running the mobs and TPS.
      • This isn't a TPS issue and affects the player who uses the systems claimed to have issues.
      • We hypothesized that this could happen with most mobs with resistance on them. (We saw that the delay happened when mobs with it had particles on them)
      • Usually, the commands run through the server to the client since Command Blocks are "block entities." 
      • This does not happen with PlayStation and PC players. We can assume that it probably does not happen on mobile as well, but we will update our findings if it also does affect mobile players somehow.
      • Mobs without particles can still be affected, either with a mob that can cause the issue or without, depending on the command line used in the world.
      • The issue inconsistently affects players, appearing randomly on their system and across various updates. We were not sure if it was a hardware issue at first until we ran across another Xbox One S player, then it was confirmed to be an issue with Minecraft and the Xbox One S and below.
      • If the player in question is a host of a world with a similar command line and/or has previously experienced using structure blocks to render structures or items into the world or used command blocks to fill, clone, create structures, or set blocks in the world does not experience the issue. However, it may be possible that it CAN still happen to other players who have the stated system.
      • This appeared in update 1.19.51 before 1.19.60 was released, and the date experienced was December 25, 2022.
      • This may be an issue with the mob's speed being inconsistent with the hitbox and entity. Paying attention to the clip seems to be the case, though probably, it is hard to confirm if we don't do enough research and testing. So this stays as a plausible theory.
      • +Main Issue: We found that commands applied on mobs affecting any families or types affect the sync of the mob's hitbox, collision, and player collision. For some reason, in multiplayer, Xbox One and Xbox One S players have a big issue with this. We think it's an overflow issue, where the mob being applied any commands will desync because of the effects of the commands stacking rather than refreshing like how every other console, including the PlayStation 4. Locally, Xbox One and Xbox One S players hosting the world DO NOT experience these issues. We think it is a multiplayer problem with how the console connects with the server, so clients may not be syncing correctly or being consistent with crossplay or shared consoles.

      The mob in question that we used to see if the player experiences these issues is my mob, the "Voidmeister." I'll provide you with all the commands for him in the chart.

      "Voidmeister" Command Usage

      execute at @e[type=wither_skeleton] run particle minecraft:eyeofender_death_explode_particle ~ ~ ~ (x2)

      execute at @e[type=wither_skeleton] run particle minecraft:end_chest ~ ~ ~

      execute at @e[type=wither_skeleton] run particle minecraft:end_chest ~ ~1.2 ~

      replaceitem entity @e[type=wither_skeleton] slot.weapon.mainhand 1 air 1 0

      execute at @e[type=wither_skeleton] run effect @e[type=wither_skeleton] resistance 1 3 true (may get re-optimized)

      execute at @e[type=wither_skeleton] run effect @e[type=wither_skeleton] absorption 2 3 true (may get re-optimized) | Tick Delay: 60

      execute at @e[type=wither_skeleton] run effect @e[type=wither_skeleton] slowness 1 1 true (may get re-optimized)

      execute at @e[type=wither_skeleton] run effect @e[type=wither_skeleton] strength 1 5 true (may get re-optimized)

      execute at @e[type=wither_skeleton] run playsound mob.wither.ambient @a ~ ~ ~ 0.25 0.7 0.1 | Tick Delay: 12

      execute at @e[type=wither_skeleton] run playsound portal.portal @a ~ ~ ~ 0.3 0.7 | Tick Delay: 64

      Use "" to include a name with spaces in the "name=" selector. If you want to create a name for the mob, use the "name=" selector.

      UPDATE: Considering that the main issue we found is because of a client de-sync or potentially a console-related issue, you can apply ANY command to the mobs (namely monsters), and it will STILL apply the de-sync. 1.20.40 made the issue significantly worse and is much more noticeable. We are now considering getting actual Xbox One players to help us with the issue to make these findings more concrete. We will publish clips to the bug report.

      We recommend that you use a world that may use up more commands or worlds that have used block entities for structures, such as structure blocks and command blocks. Due to how hard it is for us to find a root cause, we think it could be a RAM issue, possibly a leak, but that does not seem likely. That's why we are still currently experimenting whenever we can. If you want to participate in this ticket, please see the ticket. 


      If you have any evidence of the issue, please provide them. We would love it if more people showed they are also experiencing this and added to the issue. I will still add to the ticket if more findings pop up or if other people want to add to the issue.


      *Currently, it is impossible for Revemnt and I to provide the worlds we tested on due to my friend's current situations and circumstances and me taking a while to properly transfer all of my world files that are the game worlds to PC to give. Until I can adequately transfer them and send them for help with the fixes quicker, all of the information provided is the only information to go off from. We will add clips when ready.

      Clip #1: (Clip in 480p)
      Clip #2: 


      EDIT: Tables are acting up for some reason. So I'm trying to reassemble it properly. If any characters should not be there, ignore them.

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