Folia [1.21.8] Random stacktrace

Stack trace

[21:13:23] [Region Scheduler Thread #16/ERROR]: [ca.spottedleaf.moonrise.common.util.TickThread] Thread failed main thread check: Cannot asynchronously load chunks, context=[thread=Region Scheduler Thread #16,class=io.papermc.paper.threadedregions.TickRegionScheduler$TickThreadRunner,region={center=[-962, 144],world=world}], world=world, chunk_pos=[-640, 88]
java.lang.Throwable: null
	at ca.spottedleaf.moonrise.common.util.TickThread.ensureTickThread(TickThread.java:88) ~[lsfolia-1.21.8.jar:1.21.8-DEV-e49fe2f]
	at net.minecraft.server.level.ServerChunkCache.syncLoad(ServerChunkCache.java:103) ~[lsfolia-1.21.8.jar:1.21.8-DEV-e49fe2f]
	at net.minecraft.server.level.ServerChunkCache.getChunkFallback(ServerChunkCache.java:156) ~[lsfolia-1.21.8.jar:1.21.8-DEV-e49fe2f]
	at net.minecraft.server.level.ServerChunkCache.getChunk(ServerChunkCache.java:330) ~[lsfolia-1.21.8.jar:1.21.8-DEV-e49fe2f]
	at net.minecraft.world.level.Level.getChunk(Level.java:1028) ~[lsfolia-1.21.8.jar:1.21.8-DEV-e49fe2f]
	at net.minecraft.world.level.Level.getChunkAt(Level.java:1017) ~[lsfolia-1.21.8.jar:1.21.8-DEV-e49fe2f]
	at net.minecraft.world.level.Level.getFluidState(Level.java:1396) ~[lsfolia-1.21.8.jar:1.21.8-DEV-e49fe2f]
	at net.minecraft.world.level.LevelReader.isWaterAt(LevelReader.java:157) ~[lsfolia-1.21.8.jar:1.21.8-DEV-e49fe2f]
	at net.minecraft.world.entity.animal.axolotl.AxolotlAi.canSetWalkTargetFromLookTarget(AxolotlAi.java:145) ~[lsfolia-1.21.8.jar:1.21.8-DEV-e49fe2f]
	at net.minecraft.world.entity.ai.behavior.SetWalkTargetFromLookTarget.lambda$create$2(SetWalkTargetFromLookTarget.java:19) ~[lsfolia-1.21.8.jar:1.21.8-DEV-e49fe2f]
	at net.minecraft.world.entity.ai.behavior.declarative.BehaviorBuilder$1.trigger(BehaviorBuilder.java:44) ~[lsfolia-1.21.8.jar:1.21.8-DEV-e49fe2f]
	at net.minecraft.world.entity.ai.behavior.OneShot.tryStart(OneShot.java:17) ~[lsfolia-1.21.8.jar:1.21.8-DEV-e49fe2f]
	at net.minecraft.world.entity.ai.behavior.GateBehavior$RunningPolicy$2.apply(GateBehavior.java:144) ~[lsfolia-1.21.8.jar:1.21.8-DEV-e49fe2f]
	at net.minecraft.world.entity.ai.behavior.GateBehavior.tryStart(GateBehavior.java:60) ~[lsfolia-1.21.8.jar:1.21.8-DEV-e49fe2f]
	at net.minecraft.world.entity.ai.Brain.startEachNonRunningBehavior(Brain.java:461) ~[lsfolia-1.21.8.jar:1.21.8-DEV-e49fe2f]
	at net.minecraft.world.entity.ai.Brain.tick(Brain.java:413) ~[lsfolia-1.21.8.jar:1.21.8-DEV-e49fe2f]
	at net.minecraft.world.entity.animal.axolotl.Axolotl.customServerAiStep(Axolotl.java:334) ~[lsfolia-1.21.8.jar:1.21.8-DEV-e49fe2f]
	at net.minecraft.world.entity.Mob.serverAiStep(Mob.java:794) ~[lsfolia-1.21.8.jar:1.21.8-DEV-e49fe2f]
	at net.minecraft.world.entity.LivingEntity.aiStep(LivingEntity.java:3513) ~[lsfolia-1.21.8.jar:1.21.8-DEV-e49fe2f]
	at net.minecraft.world.entity.Mob.aiStep(Mob.java:523) ~[lsfolia-1.21.8.jar:1.21.8-DEV-e49fe2f]
	at net.minecraft.world.entity.AgeableMob.aiStep(AgeableMob.java:152) ~[lsfolia-1.21.8.jar:1.21.8-DEV-e49fe2f]
	at net.minecraft.world.entity.animal.Animal.aiStep(Animal.java:68) ~[lsfolia-1.21.8.jar:1.21.8-DEV-e49fe2f]
	at net.minecraft.world.entity.LivingEntity.tick(LivingEntity.java:3291) ~[lsfolia-1.21.8.jar:1.21.8-DEV-e49fe2f]
	at net.minecraft.world.entity.Mob.tick(Mob.java:394) ~[lsfolia-1.21.8.jar:1.21.8-DEV-e49fe2f]
	at net.minecraft.server.level.ServerLevel.tickNonPassenger(ServerLevel.java:1357) ~[lsfolia-1.21.8.jar:1.21.8-DEV-e49fe2f]
	at net.minecraft.world.level.Level.guardEntityTick(Level.java:1534) ~[lsfolia-1.21.8.jar:1.21.8-DEV-e49fe2f]
	at net.minecraft.server.level.ServerLevel.lambda$tick$4(ServerLevel.java:833) ~[lsfolia-1.21.8.jar:1.21.8-DEV-e49fe2f]
	at io.papermc.paper.threadedregions.RegionizedWorldData.forEachTickingEntity(RegionizedWorldData.java:601) ~[lsfolia-1.21.8.jar:1.21.8-DEV-e49fe2f]
	at net.minecraft.server.level.ServerLevel.tick(ServerLevel.java:814) ~[lsfolia-1.21.8.jar:1.21.8-DEV-e49fe2f]
	at net.minecraft.server.MinecraftServer.tickChildren(MinecraftServer.java:1834) ~[lsfolia-1.21.8.jar:1.21.8-DEV-e49fe2f]
	at net.minecraft.server.MinecraftServer.tickServer(MinecraftServer.java:1668) ~[lsfolia-1.21.8.jar:1.21.8-DEV-e49fe2f]
	at io.papermc.paper.threadedregions.TickRegions$ConcreteRegionTickHandle.tickRegion(TickRegions.java:407) ~[lsfolia-1.21.8.jar:1.21.8-DEV-e49fe2f]
	at io.papermc.paper.threadedregions.TickRegionScheduler$RegionScheduleHandle.runTick(TickRegionScheduler.java:418) ~[lsfolia-1.21.8.jar:1.21.8-DEV-e49fe2f]
	at ca.spottedleaf.concurrentutil.scheduler.SchedulerThreadPool$TickThreadRunner.run(SchedulerThreadPool.java:546) ~[concurrentutil-0.0.3.jar:?]
	at java.base/java.lang.Thread.run(Thread.java:1447) ~[?:?]
[21:13:23] [Region Scheduler Thread #16/ERROR]: Entity threw exception at world:-15387.5,-0.5,2303.5
java.lang.IllegalStateException: Thread failed main thread check: Cannot asynchronously load chunks, context=[thread=Region Scheduler Thread #16,class=io.papermc.paper.threadedregions.TickRegionScheduler$TickThreadRunner,region={center=[-962, 144],world=world}], world=world, chunk_pos=[-640, 88]
	at ca.spottedleaf.moonrise.common.util.TickThread.ensureTickThread(TickThread.java:89) ~[lsfolia-1.21.8.jar:1.21.8-DEV-e49fe2f]
	at net.minecraft.server.level.ServerChunkCache.syncLoad(ServerChunkCache.java:103) ~[lsfolia-1.21.8.jar:1.21.8-DEV-e49fe2f]
	at net.minecraft.server.level.ServerChunkCache.getChunkFallback(ServerChunkCache.java:156) ~[lsfolia-1.21.8.jar:1.21.8-DEV-e49fe2f]
	at net.minecraft.server.level.ServerChunkCache.getChunk(ServerChunkCache.java:330) ~[lsfolia-1.21.8.jar:1.21.8-DEV-e49fe2f]
	at net.minecraft.world.level.Level.getChunk(Level.java:1028) ~[lsfolia-1.21.8.jar:1.21.8-DEV-e49fe2f]
	at net.minecraft.world.level.Level.getChunkAt(Level.java:1017) ~[lsfolia-1.21.8.jar:1.21.8-DEV-e49fe2f]
	at net.minecraft.world.level.Level.getFluidState(Level.java:1396) ~[lsfolia-1.21.8.jar:1.21.8-DEV-e49fe2f]
	at net.minecraft.world.level.LevelReader.isWaterAt(LevelReader.java:157) ~[lsfolia-1.21.8.jar:1.21.8-DEV-e49fe2f]
	at net.minecraft.world.entity.animal.axolotl.AxolotlAi.canSetWalkTargetFromLookTarget(AxolotlAi.java:145) ~[lsfolia-1.21.8.jar:1.21.8-DEV-e49fe2f]
	at net.minecraft.world.entity.ai.behavior.SetWalkTargetFromLookTarget.lambda$create$2(SetWalkTargetFromLookTarget.java:19) ~[lsfolia-1.21.8.jar:1.21.8-DEV-e49fe2f]
	at net.minecraft.world.entity.ai.behavior.declarative.BehaviorBuilder$1.trigger(BehaviorBuilder.java:44) ~[lsfolia-1.21.8.jar:1.21.8-DEV-e49fe2f]
	at net.minecraft.world.entity.ai.behavior.OneShot.tryStart(OneShot.java:17) ~[lsfolia-1.21.8.jar:1.21.8-DEV-e49fe2f]
	at net.minecraft.world.entity.ai.behavior.GateBehavior$RunningPolicy$2.apply(GateBehavior.java:144) ~[lsfolia-1.21.8.jar:1.21.8-DEV-e49fe2f]
	at net.minecraft.world.entity.ai.behavior.GateBehavior.tryStart(GateBehavior.java:60) ~[lsfolia-1.21.8.jar:1.21.8-DEV-e49fe2f]
	at net.minecraft.world.entity.ai.Brain.startEachNonRunningBehavior(Brain.java:461) ~[lsfolia-1.21.8.jar:1.21.8-DEV-e49fe2f]
	at net.minecraft.world.entity.ai.Brain.tick(Brain.java:413) ~[lsfolia-1.21.8.jar:1.21.8-DEV-e49fe2f]
	at net.minecraft.world.entity.animal.axolotl.Axolotl.customServerAiStep(Axolotl.java:334) ~[lsfolia-1.21.8.jar:1.21.8-DEV-e49fe2f]
	at net.minecraft.world.entity.Mob.serverAiStep(Mob.java:794) ~[lsfolia-1.21.8.jar:1.21.8-DEV-e49fe2f]
	at net.minecraft.world.entity.LivingEntity.aiStep(LivingEntity.java:3513) ~[lsfolia-1.21.8.jar:1.21.8-DEV-e49fe2f]
	at net.minecraft.world.entity.Mob.aiStep(Mob.java:523) ~[lsfolia-1.21.8.jar:1.21.8-DEV-e49fe2f]
	at net.minecraft.world.entity.AgeableMob.aiStep(AgeableMob.java:152) ~[lsfolia-1.21.8.jar:1.21.8-DEV-e49fe2f]
	at net.minecraft.world.entity.animal.Animal.aiStep(Animal.java:68) ~[lsfolia-1.21.8.jar:1.21.8-DEV-e49fe2f]
	at net.minecraft.world.entity.LivingEntity.tick(LivingEntity.java:3291) ~[lsfolia-1.21.8.jar:1.21.8-DEV-e49fe2f]
	at net.minecraft.world.entity.Mob.tick(Mob.java:394) ~[lsfolia-1.21.8.jar:1.21.8-DEV-e49fe2f]
	at net.minecraft.server.level.ServerLevel.tickNonPassenger(ServerLevel.java:1357) ~[lsfolia-1.21.8.jar:1.21.8-DEV-e49fe2f]
	at net.minecraft.world.level.Level.guardEntityTick(Level.java:1534) ~[lsfolia-1.21.8.jar:1.21.8-DEV-e49fe2f]
	at net.minecraft.server.level.ServerLevel.lambda$tick$4(ServerLevel.java:833) ~[lsfolia-1.21.8.jar:1.21.8-DEV-e49fe2f]
	at io.papermc.paper.threadedregions.RegionizedWorldData.forEachTickingEntity(RegionizedWorldData.java:601) ~[lsfolia-1.21.8.jar:1.21.8-DEV-e49fe2f]
	at net.minecraft.server.level.ServerLevel.tick(ServerLevel.java:814) ~[lsfolia-1.21.8.jar:1.21.8-DEV-e49fe2f]
	at net.minecraft.server.MinecraftServer.tickChildren(MinecraftServer.java:1834) ~[lsfolia-1.21.8.jar:1.21.8-DEV-e49fe2f]
	at net.minecraft.server.MinecraftServer.tickServer(MinecraftServer.java:1668) ~[lsfolia-1.21.8.jar:1.21.8-DEV-e49fe2f]
	at io.papermc.paper.threadedregions.TickRegions$ConcreteRegionTickHandle.tickRegion(TickRegions.java:407) ~[lsfolia-1.21.8.jar:1.21.8-DEV-e49fe2f]
	at io.papermc.paper.threadedregions.TickRegionScheduler$RegionScheduleHandle.runTick(TickRegionScheduler.java:418) ~[lsfolia-1.21.8.jar:1.21.8-DEV-e49fe2f]
	at ca.spottedleaf.concurrentutil.scheduler.SchedulerThreadPool$TickThreadRunner.run(SchedulerThreadPool.java:546) ~[concurrentutil-0.0.3.jar:?]
	at java.base/java.lang.Thread.run(Thread.java:1447) ~[?:?]

Plugin and Datapack List

None that deal with entities.

Actions to reproduce (if known)

No response

Folia version

[11:24:39 INFO]: This server is running LSFolia version 1.21.8-DEV-master@e49fe2f (1970-01-01T00:00:00Z) (Implementing API version 1.21.8-R0.1-SNAPSHOT)
Error obtaining version information

(We are running a minimally modified Folia from commit https://github.com/PaperMC/Folia/commit/7a1c5c7c7c86a0071654e03d7bf82120d113ef38, but we do not touch the entity or chunk logic in any way)

Other

No response

Sep 15 '25 09:09 Teslicek

This is also happening on our sever as well, we have pretty much the same setup as Teslicek's server, here is out stack trace as well, I think they are the same.

From what I gathered our cause was from when a player logged into to the server this would happen and the server would crash

[07:32:47 ERROR]: [ca.spottedleaf.moonrise.common.util.TickThread] Thread failed main thread check: Cannot add entity off-main thread, context=[thread=Region Scheduler Thread #0,class=io.papermc.paper.threadedregions.TickRegionScheduler$TickThreadRunner,region={center=[-7, -2],world=world}], world=world, chunk_pos=[255, -151]
java.lang.Throwable: null
        at ca.spottedleaf.moonrise.common.util.TickThread.ensureTickThread(TickThread.java:88) ~[folia-1.21.8.jar:1.21.8-5-7a1c5c7]
        at ca.spottedleaf.moonrise.patches.chunk_system.level.entity.server.ServerEntityLookup.checkThread(ServerEntityLookup.java:52) ~[folia-1.21.8.jar:1.21.8-5-7a1c5c7]
        at ca.spottedleaf.moonrise.patches.chunk_system.level.entity.EntityLookup.addEntity(EntityLookup.java:409) ~[folia-1.21.8.jar:1.21.8-5-7a1c5c7]
        at ca.spottedleaf.moonrise.patches.chunk_system.level.entity.EntityLookup.addNewEntity(EntityLookup.java:393) ~[folia-1.21.8.jar:1.21.8-5-7a1c5c7]
        at ca.spottedleaf.moonrise.patches.chunk_system.level.entity.EntityLookup.addNewEntity(EntityLookup.java:389) ~[folia-1.21.8.jar:1.21.8-5-7a1c5c7]
        at net.minecraft.server.level.ServerLevel.addPlayer(ServerLevel.java:1641) ~[folia-1.21.8.jar:1.21.8-5-7a1c5c7]
        at net.minecraft.server.level.ServerLevel.addDuringTeleport(ServerLevel.java:1619) ~[folia-1.21.8.jar:1.21.8-5-7a1c5c7]
        at net.minecraft.server.level.ServerLevel.addDuringTeleport(ServerLevel.java:1613) ~[folia-1.21.8.jar:1.21.8-5-7a1c5c7]
        at net.minecraft.server.level.ServerPlayer.placeSingleSync(ServerPlayer.java:1712) ~[folia-1.21.8.jar:1.21.8-5-7a1c5c7]
        at net.minecraft.world.entity.Entity.lambda$placeInAsync$14(Entity.java:4152) ~[folia-1.21.8.jar:1.21.8-5-7a1c5c7]
        at io.papermc.paper.threadedregions.RegionizedTaskQueue$PrioritisedQueue$ChunkBasedPriorityTask.executeInternal(RegionizedTaskQueue.java:515) ~[folia-1.21.8.jar:1.21.8-5-7a1c5c7]
        at io.papermc.paper.threadedregions.RegionizedTaskQueue$PrioritisedQueue.executeTask(RegionizedTaskQueue.java:442) ~[folia-1.21.8.jar:1.21.8-5-7a1c5c7]
        at io.papermc.paper.threadedregions.RegionizedTaskQueue$RegionTaskQueueData.drainTasks(RegionizedTaskQueue.java:271) ~[folia-1.21.8.jar:1.21.8-5-7a1c5c7]
        at net.minecraft.server.MinecraftServer.tickServer(MinecraftServer.java:1645) ~[folia-1.21.8.jar:1.21.8-5-7a1c5c7]
        at io.papermc.paper.threadedregions.TickRegions$ConcreteRegionTickHandle.tickRegion(TickRegions.java:407) ~[folia-1.21.8.jar:1.21.8-5-7a1c5c7]
        at io.papermc.paper.threadedregions.TickRegionScheduler$RegionScheduleHandle.runTick(TickRegionScheduler.java:418) ~[folia-1.21.8.jar:1.21.8-5-7a1c5c7]
        at ca.spottedleaf.concurrentutil.scheduler.SchedulerThreadPool$TickThreadRunner.run(SchedulerThreadPool.java:546) ~[concurrentutil-0.0.3.jar:?]
        at java.base/java.lang.Thread.run(Thread.java:1583) ~[?:?]
[07:32:47 ERROR]: [io.papermc.paper.threadedregions.TickRegionScheduler] Region #19 centered at chunk [-7, -2] in world 'world' failed to tick:
java.lang.IllegalStateException: Thread failed main thread check: Cannot add entity off-main thread, context=[thread=Region Scheduler Thread #0,class=io.papermc.paper.threadedregions.TickRegionScheduler$TickThreadRunner,region={center=[-7, -2],world=world}], world=world, chunk_pos=[255, -151]
        at ca.spottedleaf.moonrise.common.util.TickThread.ensureTickThread(TickThread.java:89) ~[folia-1.21.8.jar:1.21.8-5-7a1c5c7]
        at ca.spottedleaf.moonrise.patches.chunk_system.level.entity.server.ServerEntityLookup.checkThread(ServerEntityLookup.java:52) ~[folia-1.21.8.jar:1.21.8-5-7a1c5c7]
        at ca.spottedleaf.moonrise.patches.chunk_system.level.entity.EntityLookup.addEntity(EntityLookup.java:409) ~[folia-1.21.8.jar:1.21.8-5-7a1c5c7]
        at ca.spottedleaf.moonrise.patches.chunk_system.level.entity.EntityLookup.addNewEntity(EntityLookup.java:393) ~[folia-1.21.8.jar:1.21.8-5-7a1c5c7]
        at ca.spottedleaf.moonrise.patches.chunk_system.level.entity.EntityLookup.addNewEntity(EntityLookup.java:389) ~[folia-1.21.8.jar:1.21.8-5-7a1c5c7]
        at net.minecraft.server.level.ServerLevel.addPlayer(ServerLevel.java:1641) ~[folia-1.21.8.jar:1.21.8-5-7a1c5c7]
        at net.minecraft.server.level.ServerLevel.addDuringTeleport(ServerLevel.java:1619) ~[folia-1.21.8.jar:1.21.8-5-7a1c5c7]
        at net.minecraft.server.level.ServerLevel.addDuringTeleport(ServerLevel.java:1613) ~[folia-1.21.8.jar:1.21.8-5-7a1c5c7]
        at net.minecraft.server.level.ServerPlayer.placeSingleSync(ServerPlayer.java:1712) ~[folia-1.21.8.jar:1.21.8-5-7a1c5c7]
        at net.minecraft.world.entity.Entity.lambda$placeInAsync$14(Entity.java:4152) ~[folia-1.21.8.jar:1.21.8-5-7a1c5c7]
        at io.papermc.paper.threadedregions.RegionizedTaskQueue$PrioritisedQueue$ChunkBasedPriorityTask.executeInternal(RegionizedTaskQueue.java:515) ~[folia-1.21.8.jar:1.21.8-5-7a1c5c7]
        at io.papermc.paper.threadedregions.RegionizedTaskQueue$PrioritisedQueue.executeTask(RegionizedTaskQueue.java:442) ~[folia-1.21.8.jar:1.21.8-5-7a1c5c7]
        at io.papermc.paper.threadedregions.RegionizedTaskQueue$RegionTaskQueueData.drainTasks(RegionizedTaskQueue.java:271) ~[folia-1.21.8.jar:1.21.8-5-7a1c5c7]
        at net.minecraft.server.MinecraftServer.tickServer(MinecraftServer.java:1645) ~[folia-1.21.8.jar:1.21.8-5-7a1c5c7]
        at io.papermc.paper.threadedregions.TickRegions$ConcreteRegionTickHandle.tickRegion(TickRegions.java:407) ~[folia-1.21.8.jar:1.21.8-5-7a1c5c7]
        at io.papermc.paper.threadedregions.TickRegionScheduler$RegionScheduleHandle.runTick(TickRegionScheduler.java:418) ~[folia-1.21.8.jar:1.21.8-5-7a1c5c7]
        at ca.spottedleaf.concurrentutil.scheduler.SchedulerThreadPool$TickThreadRunner.run(SchedulerThreadPool.java:546) ~[concurrentutil-0.0.3.jar:?]
        at java.base/java.lang.Thread.run(Thread.java:1583) ~[?:?]
[07:32:47 INFO]: [RegionShutdownThread] Awaiting scheduler termination for 60s...
[07:32:47 INFO]: [RegionShutdownThread] Scheduler halted
[07:32:47 INFO]: Stopping server

We managed to fix the problem by deleting the players data in the playerData folder of the world.

Oct 12 '25 10:10 PastaBake

These sorts of errors generally occur when something teleports the player in an place in which teleporting the player causes the server to trip up

Oct 12 '25 16:10 electronicboy

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[1.21.8] Random stacktrace

Stack trace

Plugin and Datapack List

Actions to reproduce (if known)

Folia version

Other

Folia
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