Moonrise is the prime culprit

[StoodMusic58914]

Stack trace

Plugin and Datapack List

Only have plugin!

pl
[10:28:58 INFO]: ℹ Server Plugins (43):
[10:28:58 INFO]: Paper Plugins (4):
[10:28:58 INFO]: - AdvancedServerList, MCKotlin-Paper, paper-language-kotlin, surf-serverbrand-customizer
[10:28:58 INFO]: Bukkit Plugins (39):
[10:28:58 INFO]: - ActionGlass, AnarchySpawn, AntiCheatAddition, AntiLoggedInFromAnotherLocation, AttackCooldownRemover, AttributeSwapFixer, BlockChat, BlockReports, Bunnysquad, BushRehab
[10:28:58 INFO]: LHTab, Milk, NewJoinMessages, NoChatLagServer, NoSleep, OtherBedRegen, OxygenGamemodeLock, packetevents, ProtocolLib, ReducedDebugInfo

Actions to reproduce (if known)

Can I add the repair update to papermc 1.21.11?
Moonrise is a big problem
Some cheating clients, such as PacketFly, can also experience the same crash

Paper version

ver
[10:29:28 INFO]: Checking version, please wait...
[10:29:28 INFO]: This server is running Paper version 1.21.11-132-ver/1.21.11@c5eb079 (2026-05-11T11:43:09Z) (Implementing API version 1.21.11-R0.1-SNAPSHOT)
You are running the latest version
Previous version: 1.21.11-131-6d5b910 (MC: 1.21.11)

Other

core conclusion
Your Paper 1.21.11 server thread is stuck (Watchdog timeout with no response). Root cause: Moonrise optimization mod + Zombie entity push logic deadlock/infinite entity traversal, causing the server main thread to hang at the getPushableEntities step, resulting in server unresponsiveness and triggering a Watchdog crash.

server: CPU 12 core RAM: 20GB

[StoodMusic58914]

This is a problem with Moonrise
and
#132
2026/5/11 19:43:09
c5eb079
Fork friendly byte buf correctly
paper-1.21.11-132.jar
The release is completely unrelated

[StoodMusic58914]

The symptoms are simple
A certain core of the CPU is running at 100% lag
[10:33:45 INFO]: UUID of player StoodMusic58914 is d1793670-3689-3b2a-8b70-c5ecabd45331
[10:33:50 WARN]: [ca.spottedleaf.moonrise.patches.chunk_system.level.entity.EntityLookup] Entity uuid already exists: 64b08d5b-9cec-4a20-8cf9-53dfb04c815e, mapped to Skeleton['Skeleton'/9295, uuid='64b08d5b-9cec-4a20-8cf9-53dfb04c815e', l='ServerLevel[world]', x=-196.50, y=79.92, z=301.35, cpos=[-13, 18], tl=0, v=false], can't add Skeleton['Skeleton'/29296, uuid='64b08d5b-9cec-4a20-8cf9-53dfb04c815e', l='ServerLevel[world]', x=-196.50, y=79.92, z=301.35, cpos=[-13, 18], tl=0, v=false]
Moonrise crashes again after entering the same chunk

[purpurcof]

Need a crash log, otherwise it's useless issue

[purpurcof]

Also looking at your list of plugins, it's just awful.

[StoodMusic58914]

kill @e
kill @e
kill @e
kill @e
kill @e
kill @e
[10:44:05 INFO]: UUID of player SM_Games is 6adde1b9-ac7d-37a4-8c21-a58b5dd98e0b
kill @e
kill @e
kill @e
kill @e
kill @e
kill @e
kill @e
[10:44:07 INFO]: Killed 31 entities
kill @e
kill @e
kill @e
[10:44:07 INFO]: Killed 718 entities
[10:44:07 INFO]: Killed 573 entities
kill @e
kill @e
kill @e
kill @e
kill @e
kill @e
kill @e
kill @e
kill @e

kill @e
kill @e
kill @e
kill @e
kill @e
kill @e
[10:44:10 INFO]: Killed 28432 entities
kill @Ekill @e
[10:44:10 INFO]: Killed 28449 entities
kill @e
[10:44:10 INFO]: Expected whitespace to end one argument, but found trailing data
kill @Ekill @e<--[HERE]
kill @e
kill @e
kill @e
kill @e
[10:44:11 INFO]: Killed 14545 entities
kill @e
[10:44:11 INFO]: Killed 10364 entities
kill @e
kill @e
kill @e
kill @e
kill @e
kill @e
kill @e
kill @e
[10:44:13 INFO]: [+] SM_Games joined the server.
Welcome to SM.SMP
kill @e
[10:44:13 INFO]: SM_Games[/127.0.0.1:38053] logged in with entity id 1 at ([world]-196.60162842991355, 70.0, 301.76660559070257)
kill @e
kill @e
kill @e
kill @Ekill @e

[10:44:14 INFO]: Killed SM_Games
[10:44:14 INFO]: Killed SM_Games

kill @e
[10:44:15 INFO]: Killed SM_Games
[10:44:15 INFO]: Killed SM_Games
[10:44:15 INFO]: Expected whitespace to end one argument, but found trailing data
kill @Ekill @e<--[HERE]
[10:44:15 INFO]: Killed SM_Games
kill @e
kill @e
kill @e
kill @e
[10:44:15 INFO]: Killed 31 entities
[10:44:15 INFO]: Killed 47 entities
[10:44:15 INFO]: Killed SM_Games
[10:44:15 INFO]: Killed SM_Games
kill @Ekill @e
kill @e
kill @e
kill @e
kill @e
kill @e
kill @e
[10:44:17 INFO]: Expected whitespace to end one argument, but found trailing data
kill @Ekill @e<--[HERE]
kill @e
[10:44:17 INFO]: Killed 581 entities
[10:44:17 INFO]: Killed 796 entities
[10:44:17 INFO]: Killed SM_Games
[10:44:17 INFO]: Killed SM_Games
[10:44:17 INFO]: Killed SM_Games
[10:44:17 INFO]: Killed SM_Games
[10:44:17 INFO]: Killed SM_Games
kill @e
[10:44:18 INFO]: Killed SM_Games

[StoodMusic58914]

Yes
I used entity cleaning to restore the issue
I hope papermc 1.21.11 can fix this issue
Updated to the support series of papermc 1.21.11

[purpurcof]

kill @e
kill @e
kill @e
kill @e
kill @e
kill @e
[10:44:05 INFO]: UUID of player SM_Games is 6adde1b9-ac7d-37a4-8c21-a58b5dd98e0b
kill @e
kill @e
kill @e
kill @e
kill @e
kill @e
kill @e
[10:44:07 INFO]: Killed 31 entities
kill @e
kill @e
kill @e
[10:44:07 INFO]: Killed 718 entities
[10:44:07 INFO]: Killed 573 entities
kill @e
kill @e
kill @e
kill @e
kill @e
kill @e
kill @e
kill @e
kill @e
kill @e
kill @e
kill @e
kill @e
kill @e
kill @e
[10:44:10 INFO]: Killed 28432 entities
kill @Ekill @e
[10:44:10 INFO]: Killed 28449 entities
kill @e
[10:44:10 INFO]: Expected whitespace to end one argument, but found trailing data
kill @Ekill @e<--[HERE]
kill @e
kill @e
kill @e
kill @e
[10:44:11 INFO]: Killed 14545 entities
kill @e
[10:44:11 INFO]: Killed 10364 entities
kill @e
kill @e
kill @e
kill @e
kill @e
kill @e
kill @e
kill @e
[10:44:13 INFO]: [+] SM_Games joined the server.
Welcome to SM.SMP
kill @e
[10:44:13 INFO]: SM_Games[/127.0.0.1:38053] logged in with entity id 1 at ([world]-196.60162842991355, 70.0, 301.76660559070257)
kill @e
kill @e
kill @e
kill @Ekill @e

[10:44:14 INFO]: Killed SM_Games [10:44:14 INFO]: Killed SM_Games

kill @e
[10:44:15 INFO]: Killed SM_Games
[10:44:15 INFO]: Killed SM_Games
[10:44:15 INFO]: Expected whitespace to end one argument, but found trailing data
kill @Ekill @e<--[HERE]
[10:44:15 INFO]: Killed SM_Games
kill @e
kill @e
kill @e
kill @e
[10:44:15 INFO]: Killed 31 entities
[10:44:15 INFO]: Killed 47 entities
[10:44:15 INFO]: Killed SM_Games
[10:44:15 INFO]: Killed SM_Games
kill @Ekill @e
kill @e
kill @e
kill @e
kill @e
kill @e
kill @e
[10:44:17 INFO]: Expected whitespace to end one argument, but found trailing data
kill @Ekill @e<--[HERE]
kill @e
[10:44:17 INFO]: Killed 581 entities
[10:44:17 INFO]: Killed 796 entities
[10:44:17 INFO]: Killed SM_Games
[10:44:17 INFO]: Killed SM_Games
[10:44:17 INFO]: Killed SM_Games
[10:44:17 INFO]: Killed SM_Games
[10:44:17 INFO]: Killed SM_Games
kill @e
[10:44:18 INFO]: Killed SM_Games

There is no crash here, close the issue and don't waste others' time

[Malfrador]

Thanks for the issue report, but this is most likely some kind of performance issue and not a bug.
It looks like you are repeatedly running the @e selector. This is incredibly bad for performance, as it will iterate through all entities on the server every single time

If you need further help, please use the #paper-help channel on our discord server for support with this.