Experience orb position client-server desync

Happens to me on my client SMP games every once in a while.

I have noticed this since 1.2.5. Very annoying when you throw a bottle of enchanting.

Yes i've noticed this since 1.4.5. Experience orbs swirling in front of face that can't be collected. Playing on PC, single player survival, no mods. Quite rare and don't know what triggers it. Sometimes they appear just after loading a world.

The cause is simple. The orb "moves" towards the player, and the player "collects". But this is only client side.
The orb itself has not moved, and is still at it's original drop location.
Unless the player walks over that particular location / block, the "collected" orb stays flying around the player.
The quick "fix" is to walk around all the blocks where the orbs were, to make sure you've collected them all.

Seems to be related to MC-4.

In 1.5.1, the orb position seems to be synced once every second or so.

Which makes it really easy to demonstrate that there is problem with halfslabs. The client seems to think that the orbs can travel up a halfslab, while the server thinks not.

With 1.5.1 SSP, I have an xp grinder that uses half-slabs. On the sides where the half-slabs are on the top half of a block, the exp orbs are able to pass beneath the half-slabs and are absorbed normally. On sides where the half-slabs are on the bottom of the block, the exp orbs travel toward me, circle around, then reappear inside the grinder and repeat this cycle in an infinite loop (or until they despawn, I suppose.) If I break any of the lower half-slabs on the side I'm facing, or if I move around to another side of the grinder where the half-slabs are on the upper half of their block, the orbs immediately travel through the lower gap and are absorbed. I believe the credit for the exp does appear on the HUD the first time the orbs exit the grinder; it is only the visual orb entity that fails to disappear. Thus it seems orbs are able to travel through the lower half of a block, but not the upper half.

If all of the half-slabs are on the bottom of their blocks, then the orbs never get absorbed and will continue to cycle in and out of the grinder until they despawn. Walking around the grinder has no effect and it does not matter where I walk or stand.

Tested 1.3.2, 1.4.7, and 1.5.2. Definitely happens much more often in 1.4 and 1.5 than in 1.3

Still in 1.7.2.

Just updated to 1.7.4 and it seems to be worse than ever. Most of the orbs keeps flying around your head (I'm getting sea sick)

Is this still a concern in the latest Minecraft version 14w21b? If so, please update the affected versions in order to best aid Mojang ensuring bugs are still valid in the latest releases/pre-releases.

Many bugs in Minecraft are cause by the internal server system, if Mojang back to the old singleplayer that was great, a lots of bugs in Minecraft can be fixed, examples: singleplayer lag, mob clipping, dropped items clipping, strange mob moves, missing travel.ogg sound, etc... It's only a suggestion, I would be very grateful if Mojang decide to remove the internal servers (or make it optional).

I disagree with removal of internal server (it has made modding SO MUCH EASIER) but agree that the current state of singleplayer is quite dismal. They need to go back to 1.2.5 and play it for a little and take note of how everything wasn't broken and then try to get that back in.

The internal server has many more upsides than downsides. It has helped to make development much faster, as the singleplayer coding and the multiplayer coding can be done simultaneously and improved the stability of servers too.

I agree that it's very beneficial, I'm just saying that more effort should've been put in to make the internal server experience match that of 1.2.5, because it's far from doing so.

Is this still a concern in the current Minecraft version 1.8.1 Prerelease 3 / Launcher version 1.5.3 or later? If so, please update the affected versions in order to best aid Mojang ensuring bugs are still valid in the latest releases/pre-releases.

This actually seems to be fixed in 1.8.1-pre3.

Fixing it as such, thanks.

New report in 1.8.1 from MC-76071

still happening in 1.8.3 (http://i.imgur.com/NNkg432.png) and it's really REALLY annoying when it completely blinds you, like what seems to happen to me EVERY TIME I go mob farming

Confirmed for

• 1.8.3 when you throw a bottle of enchanting, the XP orbs display first all facing south (that is not really the bug) but after this get a random direction (also not the bug) and sometimes get spread for about 5 blocks

Might relate to MC-12013

Nah, MC-12013 is safely and completely solved (I made a mod to fix it before Vanilla patched it so I know what that bug is)
This bug is just an extension / special case of MC's entity syncing system being derpy in general (client and server still not matching some code, etc.). By extension this and the item drops appearing in wrong place bug and the boat desync bug are all the result of a derpy synchronizations system.

This happens to me with my cave spider exp farm in 1.8.8

Affects 15w47c

Confirmed for 1.8.9 and 15w51b.

Confirmed for 1.10. I've attached a screenshot of a setup with which this can be reproduced (other ways that are mentioned in this report don't work anymore).
The top glass block on the left side is at the coordinates -120 57 2, the rest of the glass box is in the direction of negative x.
First command block (right) contains "gamemode 3 @p", then there is a repeater to a little tower with the following commands:
gamemode 1 @p
teleport @p -119 57 2 90 0
summon XPOrb -121 57 2
This positions the nearest player left of the top glass block on the left and an XP orb directly on the other side, above the water source.
Result: The XP Orb flies in a well visible bow above the player before it gets reset to its server position.

Confirmed for 1.10.1.

Attached a world with the setup you described to reproduce this

Does this problem affect Minecraft 1.11?

Attached an screenshot showing an easy test setup.

Still in 1.11.2

Screen shot shows the same bug with hoppers. The orb close to the crosshair will now track me (sideways) when i move but it will not go "over the edge" and to me. However, if i log out and back in it will start to fly to me repeatedly but it cant be picked up (since i already got it before i guess).

@unknown please don't attach screenshots made with modified versions of Minecraft. These are useless to us.