My log is spammed with these:
[16:05:17] [Server thread/WARN]: Tried to add entity with duplicate UUID c9904869-a99c-49eb-b746-b2b128f607b0
One way to reproduce
Build and turn on a nether portal.
Push a pig into the portal.
The pig disappeared and in the launcher there is the warning "Tried to add entity with duplicate UUID..."
It works with any entity that can teleport besides the player and with end and nether portals.
There might also be other situations in which this bug appears but this is one where it shouldn't for sure. To be clear: This deletes entities instead of porting them!
Possible reason for this bug
I assume that the reason this is happening, is that when entities are teleported to an other dimension they get duplicated and their clone is sent to the other dimension.
The cloned entity probably has the same UUID and therefore causes this problem.
Moderator node:
Also occuring without any portals, see comment
Confirmed in 15w31c. No portals at all. Plain survival on new world, no commands, no eggs. Heavy console spamming (4 to 8 errors/minute) causing significant server lags.
and MC-84645
I mean, like this:
[16:05:24] [Server thread/WARN]: Tried to add entity with duplicate UUID 9ab31ebc-7c46-48bd-b544-427d4bc862a0
[16:05:24] [Server thread/WARN]: Tried to add entity with duplicate UUID 0daf1cc6-5dc4-4029-8365-90e7b31b67c3
[16:05:24] [Server thread/WARN]: Tried to add entity with duplicate UUID 7e8f3c03-e0a4-4827-90b9-74ef80799eeb
[16:05:24] [Server thread/WARN]: Tried to add entity with duplicate UUID 73f26e4c-1d4b-453c-94b5-840b6493bfa7
[16:05:24] [Server thread/WARN]: Tried to add entity with duplicate UUID 22e37536-a519-423d-aee7-ffaeb8c15c99
[16:05:24] [Server thread/WARN]: Tried to add entity with duplicate UUID ce23a2c9-ed5d-4fa6-9fac-1eff3cde177b
[16:05:24] [Server thread/WARN]: Tried to add entity with duplicate UUID 72cb186a-9b82-4727-bfe2-0996aeda64b3
[16:05:24] [Server thread/WARN]: Tried to add entity with duplicate UUID 5735f2c2-0ed4-4247-af20-83add75f6734
[16:05:24] [Server thread/WARN]: Tried to add entity with duplicate UUID 9aa74053-a63e-437c-b423-a7043cb0a470
[16:05:24] [Server thread/WARN]: Tried to add entity with duplicate UUID 314fccd6-b476-4f80-b9ce-516dc80f7154
[16:05:24] [Server thread/WARN]: Tried to add entity with duplicate UUID 1cc80483-084b-4a7f-84fb-05b6ad0fda3c
[16:05:24] [Server thread/WARN]: Tried to add entity with duplicate UUID 18b6f6fc-de44-4f9e-9475-97a40fdff532
[16:05:24] [Server thread/WARN]: Tried to add entity with duplicate UUID b8e2c921-7ead-4e1a-a5f6-bf5c9395993f
[16:05:24] [Server thread/WARN]: Tried to add entity with duplicate UUID 8b6b245f-5f16-48ce-9cc6-794c3d982283
[16:05:24] [Server thread/WARN]: Tried to add entity with duplicate UUID 2a4ea85d-5aab-42db-9a18-e99acafb4028
[16:05:24] [Server thread/WARN]: Tried to add entity with duplicate UUID a33ea6b7-dc02-446d-a85e-5a7fbcae9c10
[16:05:24] [Server thread/WARN]: Tried to add entity with duplicate UUID 4bac6bac-ecbc-4a8b-9de3-fc4f08b361cf
[16:05:24] [Server thread/WARN]: Tried to add entity with duplicate UUID 2c53b3f6-9114-4e59-8a1d-e2cc028bdb45
[16:05:31] [Server thread/WARN]: Tried to add entity with duplicate UUID b66bcfa4-fb50-4691-89ff-5add1db3bdcb
[16:05:31] [Server thread/WARN]: Tried to add entity with duplicate UUID c52bc750-fb20-477d-8901-0f54aa2afc0d
[16:05:31] [Server thread/WARN]: Tried to add entity with duplicate UUID d259f2cb-4070-403f-bcd2-823b2be1fca6
[16:05:31] [Server thread/WARN]: Tried to add entity with duplicate UUID ebc8a4a0-5483-4a77-bc1b-02d3076590da
[16:05:31] [Server thread/WARN]: Tried to add entity with duplicate UUID 4b8fb5f1-b085-4c14-8f7d-3f6031879181
[16:05:31] [Server thread/WARN]: Tried to add entity with duplicate UUID 8f8a508c-dbbf-4d9b-888f-da9af3405718
[16:05:31] [Server thread/WARN]: Tried to add entity with duplicate UUID e540eae6-5fb7-4fd1-8171-d09582cf9b7c
[16:05:31] [Server thread/WARN]: Tried to add entity with duplicate UUID 6f96de8c-6c29-4a53-9d65-e36949b063e2
[16:05:31] [Server thread/WARN]: Tried to add entity with duplicate UUID 53bf038b-685e-4293-91c7-3806f5d212f7
[16:05:33] [Server thread/WARN]: Tried to add entity with duplicate UUID b04b6840-f6f3-4301-83cc-0f2992e7c30e
[16:05:33] [Server thread/WARN]: Tried to add entity with duplicate UUID 7739bad1-a3ca-4c02-b2f5-823f67e9fc7e
[16:05:33] [Server thread/WARN]: Tried to add entity with duplicate UUID 717a78b9-ab22-4908-8481-0c06f0ac5ea3What is this?
Linked issues
is duplicated by 8
relates to 4
MC-83350
Entities teleporting through a portal disappear instead of teleporting.
Resolved
MC-85285
Entities removed from world unless in mine carts
Resolved
MC-87560
Possible spawning of entities with same UUID causes entity to not spawn
Resolved
MC-88922
Console spam "Tried to add entity with pending removal and duplicate UUID"
Resolved
Attachments
Comments 49
This is to prevent multiple entities from having the same UUID, for example try using the following command twice:
/summon Pig ~ ~ ~ {UUIDLeast:0,UUIDMost:0}Possible bug
However this message should definitely not appear so often! As the UUID is random chances that two entities with the same UUID exist should be way lower.
Possible problem
Currently it did not happen to me, but I am afraid that Minecraft might cancel a /summon command if it picks by random an already existing UUID. If so that might break many command block contraptions as this bug can't be handled or even prevented by the player.
Minecraft should keep trying summoning a mob if no explicit UUID is given.
Way to reproduce
Build and turn on a nether portal.
Push a pig into the portal.
The pig disappeared and in the launcher there is the warning "Tried to add entity with duplicate UUID..."
It works with any entity that can teleport besides the player and with end and nether portals.
There might also be other situations in which this bug appears but this is one where it shouldn't for sure. To be clear: This deletes entities instead of porting them!
Possible reason for this bug
I assume that the reason this is happening, is that when entities are teleported to an other dimension they get duplicated and their clone is sent to the other dimension.
The cloned entity probably has the same UUID and therefore causes this problem.
We are getting this error with out using any summon, eggs and or cheat commands. Just testing pure survival. I would imagine in our case it would be natural spawners causing the issue.
The issue is so frequent that it is causing poor server performance.
I am getting this quite a lot for every player UUID on the sevrer console, which is anywhere from 20-40 players
looked on the tracker quickly, saw no reports past 15w33a, give an example
my server is not having this issue at all anymore
if you mean "Tried to add entity with pending removal and duplicate UUID" that's MC-88922 and was a debug message for the code that @unknown wrote to fix this
I still get this issue on a 1.9.2 server: (Is this another bug or the same one ?)
[15:35:35] [Server thread/WARN]: Keeping entity Zombie that already exists with UUID 4b8f8373-7dcf-4863-97b7-b970749d8da3
[15:35:35] [Server thread/WARN]: Keeping entity Zombie that already exists with UUID 39332185-ef35-44b6-b052-29746acacac3
[15:35:35] [Server thread/WARN]: Keeping entity Enderman that already exists with UUID 3c3fa926-1e41-4a22-ba32-c63d24b71954
[15:35:35] [Server thread/WARN]: Keeping entity Pig that already exists with UUID 25985b03-21a5-4e9a-8ea2-4e37f59aa08a
[15:35:35] [Server thread/WARN]: Keeping entity Bat that already exists with UUID 149bb2ca-cd28-4349-9c5a-6a54765b9cca
that's MC-95649
michael
I got a spam of "Tried to add entity with duplicate UUID" too when I was spawning a bunch of Guardians from eggs to test. 15w31a