The bug
Trying to interact with an entity which is 3 or more blocks away without seeing its eyes only causes the interaction to happen only client-side. This can lead to ghost items or other weird behavior.
Example interactions
Interaction | Result |
|---|---|
Using a Name tag on a mob | The mob is named for client, but it can despawn, commands won't find it by the name, and the name disappears after a re-log. The name tag disappears from the inventory (survival) and returns back if you update the slot it was in |
Using a Flint and Steel on a creeper | Sound of igniting the entity |
Milking a cow or a mooshroom (MC-94008) | Ghost buckets of milk that become empty buckets if you update them |
Shearing a mooshroom | Mooshroom disappears until you re-log in |
Trying to ride a horse / llama | Player is only rotated |
How to reproduce (horse)
Summon a horse
Make sure you are three or more blocks away from it and that you cannot see its eyes
Right click the horse
→ The rotation of the horse is applied to you but you did not mount the horse
How to reproduce (name tag)
Creepers in
[media]represent 3 cases (from left to right) in which the mob is behind (glass) blocks.
In the 1st and the 2nd case you should stand on sandstone blocks or top of sandstone stairs to reproduce the bug.
In the 3rd case you should be at least 2.625 blocks higher than the mob (0.625 = 6 snow layers) and 1 block away from it
Code analysis
Based on 1.11.2 decompiled using MCP 9.35 rc1
The method net.minecraft.network.NetHandlerPlayServer.processUseEntity(CPacketUseEntity) requires the player to see the eyes of the entity (method EntityLivingBase.canEntityBeSeen(Entity)). This check might make no sense because you are not always trying to interact with the head of an entity.
Linked issues
is duplicated by 10
MC-94008
Milk buckets restack after milking while standing on a ladder
Resolved
MC-105844
Creeper specific despawning when named with a nametag?
Resolved
MC-107089
/kill @e[name=...] not targeting newly named mobs
Resolved
MC-114258
Unable to perminently name ghast
Resolved
MC-118185
Trying to interact with entity 3 or more blocks away without seeing its eyes only interacts client-side
Resolved
relates to 3
MC-95720
Client-server desync on seemingly invalid block placement
Open
MC-27535
Mobs can sometimes still despawn, even if named with a name tag
Resolved
MC-79925
null hitResult when no entity or block is in focus while looking through blocks without the ray trace intersecting the blocks themselves
Resolved
Attachments
Comments 30
In the table it says that the name disappears after relog and the tag is returned, but none of that happened on my side, and other people were able to see the named entity :/ (someone even left a sign telling me how to move it without a leash since leashes are bugged for ocelots and wolves)
also worth noting that my ocelot did not despawn for 2 days. I relogged multiple times during that period and even closed the game entirely several times due to lag or invalid sessions, every time she was still where I left her :/
Confirmed for 17w16b, reproduced with milk buckets, like demonstrated in MC-94008.
Shearing a mooshroom in 17w16b gives me a regular cow (and red shrooms) rightaway, the cow doesn't disappear optically? (Or did I maybe misunderstand the described issue for mooshrooms?)
The mooshroom disappears for me. Did you try to reproduce it the same way you reproduced with milk buckets?
Usually I only test shearing a mooshroom, but as it did not disappear in 1.13.1 pre-1 as usual, I also tested the milking and the nametags. Both still occur for me, but not anymore the disappearing when shearing, in 1.13.1 pre-1.
In 18w49a, the mooshroom still does not disappear anymore when shearing.
For milking, the bug still occurs (bucket shows milk, until you update it by moving the bucket in your inventory).
I believe I found this bug on 1.14.4 - in survival mode, a creeper naturally spawned in a little spot I had hollowed out of a mountain for my mule. I thought it was pretty funny, so I went and made a name tag for it, entered creative mode, gave him a nice little home and named him Henry. I then walked off not too far away (unsure, no more than 200 blocks though) and came back to see he wasn't there anymore. No explosion damage anywhere despite being surrounded by cobblestone and dirt and the entrance sealed with panes so he wouldn't aggro.
Sorry if that's too much info, but I'm not certain if I'm on the right bug page. It just sounds like a similar issue.
coschevi
Relates to MC-95720