DMC client parameters crush server when player join

[Beengoo]

Stack trace

[19:55:20 INFO]: Done (7.443s)! For help, type "help"
[19:55:29 INFO]: UUID of player beengoo is e1d52487-74fe-46db-948a-82ffa057a9b0
[19:55:30 INFO]: beengoo joined the game
[19:55:30 INFO]: beengoo[/127.0.0.1:53314] logged in with entity id 95 at ([world]-56.94311053857109, 85.49313574198008, 31.53544797766236)
[19:55:30 ERROR]: [io.papermc.paper.threadedregions.TickRegionScheduler] Region #1 centered at chunk [-4, 1] in world 'world' failed to tick:
net.minecraft.ReportedException: Exception ticking world
        at net.minecraft.server.MinecraftServer.tickChildren(MinecraftServer.java:1934) ~[folia-1.21.11.jar:1.21.11-3-eee7128]
        at net.minecraft.server.MinecraftServer.tickServer(MinecraftServer.java:1744) ~[folia-1.21.11.jar:1.21.11-3-eee7128]
        at net.minecraft.server.dedicated.DedicatedServer.tickServer(DedicatedServer.java:429) ~[folia-1.21.11.jar:1.21.11-3-eee7128]
        at io.papermc.paper.threadedregions.TickRegions$ConcreteRegionTickHandle.tickRegion(TickRegions.java:485) ~[folia-1.21.11.jar:1.21.11-3-eee7128]
        at io.papermc.paper.threadedregions.TickRegionScheduler$RegionScheduleHandle.runTick(TickRegionScheduler.java:480) ~[folia-1.21.11.jar:1.21.11-3-eee7128]
        at ca.spottedleaf.concurrentutil.scheduler.EDFSchedulerThreadPool$TickThreadRunner.run(EDFSchedulerThreadPool.java:526) ~[concurrentutil-0.0.8.jar:?]
        at java.base/java.lang.Thread.run(Thread.java:1474) ~[?:?]
Caused by: java.lang.UnsupportedOperationException
        at net.minecraft.server.level.ChunkMap.forEachEntityTrackedBy(ChunkMap.java:1117) ~[folia-1.21.11.jar:1.21.11-3-eee7128]
        at net.minecraft.util.debug.TrackingDebugSynchronizer.addSubscriber(TrackingDebugSynchronizer.java:62) ~[folia-1.21.11.jar:1.21.11-3-eee7128]
        at net.minecraft.util.debug.TrackingDebugSynchronizer.tick(TrackingDebugSynchronizer.java:42) ~[folia-1.21.11.jar:1.21.11-3-eee7128]
        at net.minecraft.util.debug.LevelDebugSynchronizers.tick(LevelDebugSynchronizers.java:63) ~[folia-1.21.11.jar:1.21.11-3-eee7128]
        at net.minecraft.server.level.ServerLevel.tick(ServerLevel.java:896) ~[folia-1.21.11.jar:1.21.11-3-eee7128]
        at net.minecraft.server.MinecraftServer.tickChildren(MinecraftServer.java:1929) ~[folia-1.21.11.jar:1.21.11-3-eee7128]
        ... 6 more

Plugin and Datapack List

pl
[19:59:10 INFO]: ℹ Server Plugins (0):

Actions to reproduce (if known)

1. Run minecraft client with following parameters: -DMC_DEBUG_ENABLED -DMC_DEBUG_POI -DMC_DEBUG_PATHFINDING
2. Join server
3. give yourself operator
4. Server crash

Folia version

/version
[20:00:08 INFO]: Checking version, please wait...
[20:00:08 INFO]: This server is running Folia version 1.21.11-3-ver/1.21.11@eee7128 (2025-12-21T23:35:28Z) (Implementing API version 1.21.11-R0.1-SNAPSHOT)
You are running the latest version
Previous version: 1.21.11-2-39b4122 (MC: 1.21.11)

Other

No response

[ocelotpotpie]

This method isn't supported by Folia.

[Beengoo]

At least make it ignore parameters, not crush a whole server

[Dueris]

This is a genuine issue and should be reopened. This method is not called by a plugin or something else, and is called by Vanilla source code, and the call should just be skipped or ignored, or completely removed by the region threading base patch.