The bug

Players are removed from the list of loaded entities and the EntityTracker stops tracking them when they teleport out of non-spawn chunks which are not loaded afterwards anymore into currently unloaded chunks. This causes all kind of desynchronizations for the client and results in the @e selector not finding the player anymore ( @a , @r and @p still do).

Desynchronization examples

For any level of speed/slowness, it doesn't increase/decrease your walking speed, nor FOV and if you had speed or slowness before the glitch happens the speed/slowness will also stay after you clear it. (It won't show any particles or a tab in the GUI saying that you have the effect but your FOV is still increased/decreased and you still walk faster/slower)

Invisibility doesn't work.

Switching to spectator mode makes your head completely nontransparent ( MC-93377 ) and when switching from spectator to another makes you invisible. ( MC-92324 )

) and when switching from spectator to another makes you invisible. ( ) You don't take knockback from any damage. ( MC-98210 )

) You can't hear any damage sounds.

Elytras won't work ( MC-89994 ) which might be the cause of MC-90035.

) which might be the cause of MC-90035. Targeting with @e and @r[type=player] becomes unreliable. ( MC-100369 )

) If you have some armor equipped, then teleport, changing the armor values (changing, adding, removing) makes your armor points stay the same.

Players will be invisible. ( MC-91236 )

) Potion effects are displayed incorrectly, went through a teleporter after getting absorption, and even after the absorption wore off minutes later, the particle effects from it were there.

Health is displayed incorrectly, health-boost/absorption before teleporting, and extra hearts did not show after teleporting.

Attack Indicator displays wrong animation ( MC-97169 )

) Main hand is always your right hand ( MC-142135 )

) Killing an entity with a bow and arrow will not count as the player's kill

Player becomes stuck in bed

List by Spake Miner

How to reproduce

The main steps are always

Use setup steps provided for the specific reproduction case Teleport away from any chunks which remain loaded after you teleport, example: spawn chunks, chunks with other player, chunks with hoppers... /tp ~ ~ ~100000 Teleport away from these chunks making sure they get unloaded once you teleported /tp ~ ~ ~100000 Use reproduction steps provided for the specific reproduction case

Potion effects modifiers are not updated for client

Reproduction steps

Give yourself speed or slowness which both modify the movement speed /effect @p speed 10000 10 true Walk around

→ You will notice that you walk with normal movement speed

Potion effect particles are not updated

Setup steps

Give yourself for example night vision /effect @p night_vision 1000 1

Reproduction steps

Clear the potion effects /effect @p clear → You will notice that the particles remain

Actions modifying flags value

The FLAGS data parameter stores the state for some entity states:

burning

sneaking

sprinting

invisible

glowing

elytra flying

Data parameters are managed by the EntityTracker and therefor the player will not receive the change. The highlighted states cause client side problems. "Invisible" includes switching from Spectator mode to Creative mode.

Setup steps

Switch to Spectator mode or give yourself the invisibility effect

/gamemode spectator

Reproduction steps

Switch back to a different game mode

Stand in fire

Use the glowing effect /effect @p glowing 1000 1 true

Use the invisibility effect /effect @p invisibility 1000 1 true

Try using the elytra

Entity selector not finding player anymore

Reproduction steps

Use the following command

/say @e

Code analysis

Based on 1.11.2 decompiled using MCP 9.35 rc1

The problem is that the method net.minecraft.world.World.updateEntityWithOptionalForce(Entity, boolean) only updates the chunk an entity is in if the area around the entity is loaded, which causes other bugs like MC-81536 and might not be a good design as seen in MC-108469.

When the server then receives a CPacketPlayer packet before the area around the player is loaded correcting the chunk the player is in, the chunks were the player was before are unloaded. This makes the server then later remove the player from the list of loaded entities (Side note: but not loaded players) and causes the EntityTracker to stop tracking the player which means no data parameter changes are send to the player anymore.

Removing the condition for the area to be loaded could nearly completely solve this problem. It would however not solve the problem where entities teleported in unloaded chunks get lost.