Bug: Stuck on "Joining world..." until server restart

Question

Bug: Stuck on "Joining world..." until server restart

marleyinbloom opened this issue 2 months ago · 18 comments

marleyinbloom commented 2 months ago

What Feature Types Apply to This Bug?

Entity

Other Type

No response

What Type of Bug Is This?

Performance

Mod Loader

NeoForge

Mod Loader Version

21.1.201

The Aether Version

1.5.9

Is This Bug a Conflict With Another Mod?

No response

Client Log

https://gist.github.com/marleyinbloom/cd854ab14a992a49d073ed933bc50b29

Crash Report (if applicable)

No response

Steps to Reproduce

Bug seems to be related to Moas in some way but I'm uncertain of the specifics, I haven't done much in the Aether, but my players have. There is a large pen of baby Moas near the world spawn that may have something to do with it?

What You Expect To Happen

I'd expect to be able to join the server without much issue

What Actually Happened

I get stuck on the "Loading world..." screen, an error appears in the server console but nothing of note on the client end.

Additional Details

On the server end, upon joining, this error appears:

[01:15:53] [User Authenticator #24/INFO] [minecraft/ServerLoginPacketListenerImpl]: UUID of player marleyinblooom is 2a96f756-a39e-4720-ae20-d9f2812c5046
[01:15:53] [Server thread/ERROR] [minecraft/ServerPacketListener]: Failed to handle packet ServerboundSelectKnownPacks[knownPacks=[minecraft:core:1.21.1]], suppressing error
java.lang.IllegalArgumentException: Failed to serialize ResourceKey[aether:moa_type / aether:black]: Item must not be minecraft:air
        at TRANSFORMER/[email protected]/net.minecraft.core.RegistrySynchronization.lambda$packRegistry$1(RegistrySynchronization.java:39) ~[server-1.21.1-20240808.144430-srg.jar%23200!/:?] {re:classloading}
        at MC-BOOTSTRAP/[email protected]/com.mojang.serialization.DataResult$Error.getOrThrow(DataResult.java:287) ~[datafixerupper-8.0.16.jar%23100!/:?] {re:mixin}
        at TRANSFORMER/[email protected]/net.minecraft.core.RegistrySynchronization.lambda$packRegistry$2(RegistrySynchronization.java:39) ~[server-1.21.1-20240808.144430-srg.jar%23200!/:?] {re:classloading}
        at MC-BOOTSTRAP/[email protected]/it.unimi.dsi.fastutil.objects.ObjectArrayList$Spliterator.forEachRemaining(ObjectArrayList.java:955) ~[fastutil-8.5.12.jar%23111!/:?] {}
        at java.base/java.util.stream.ReferencePipeline$Head.forEach(ReferencePipeline.java:762) ~[?:?] {}
        at TRANSFORMER/[email protected]/net.minecraft.core.RegistrySynchronization.lambda$packRegistry$3(RegistrySynchronization.java:33) ~[server-1.21.1-20240808.144430-srg.jar%23200!/:?] {re:classloading}
        at java.base/java.util.Optional.ifPresent(Optional.java:178) ~[?:?] {re:mixin}
        at TRANSFORMER/[email protected]/net.minecraft.core.RegistrySynchronization.packRegistry(RegistrySynchronization.java:30) ~[server-1.21.1-20240808.144430-srg.jar%23200!/:?] {re:classloading}
        at TRANSFORMER/[email protected]/net.minecraft.core.RegistrySynchronization.lambda$packRegistries$0(RegistrySynchronization.java:26) ~[server-1.21.1-20240808.144430-srg.jar%23200!/:?] {re:classloading}
        at java.base/java.util.ArrayList.forEach(ArrayList.java:1596) ~[?:?] {re:mixin}
        at java.base/java.util.Collections$UnmodifiableCollection.forEach(Collections.java:1117) ~[?:?] {}
        at TRANSFORMER/[email protected]/net.minecraft.core.RegistrySynchronization.packRegistries(RegistrySynchronization.java:26) ~[server-1.21.1-20240808.144430-srg.jar%23200!/:?] {re:classloading}
        at TRANSFORMER/[email protected]/net.minecraft.server.network.config.SynchronizeRegistriesTask.sendRegistries(SynchronizeRegistriesTask.java:38) ~[server-1.21.1-20240808.144430-srg.jar%23200!/:?] {re:classloading}
        at TRANSFORMER/[email protected]/net.minecraft.server.network.config.SynchronizeRegistriesTask.handleResponse(SynchronizeRegistriesTask.java:51) ~[server-1.21.1-20240808.144430-srg.jar%23200!/:?] {re:classloading}
        at TRANSFORMER/[email protected]/net.minecraft.server.network.ServerConfigurationPacketListenerImpl.handleSelectKnownPacks(ServerConfigurationPacketListenerImpl.java:157) ~[server-1.21.1-20240808.144430-srg.jar%23200!/:?] {re:mixin,pl:accesstransformer:B,re:classloading,pl:accesstransformer:B,pl:mixin:APP:glitchcore.mixins.json:MixinServerConfigurationPacketListenerImpl from mod glitchcore,pl:mixin:A}
        at TRANSFORMER/[email protected]/net.minecraft.network.protocol.configuration.ServerboundSelectKnownPacks.handle(ServerboundSelectKnownPacks.java:23) ~[server-1.21.1-20240808.144430-srg.jar%23200!/:?] {re:classloading}
        at TRANSFORMER/[email protected]/net.minecraft.network.protocol.configuration.ServerboundSelectKnownPacks.handle(ServerboundSelectKnownPacks.java:11) ~[server-1.21.1-20240808.144430-srg.jar%23200!/:?] {re:classloading}
        at TRANSFORMER/[email protected]/net.minecraft.network.protocol.PacketUtils.lambda$ensureRunningOnSameThread$0(PacketUtils.java:27) ~[server-1.21.1-20240808.144430-srg.jar%23200!/:?] {re:classloading}
        at TRANSFORMER/[email protected]/net.minecraft.server.TickTask.run(TickTask.java:18) ~[server-1.21.1-20240808.144430-srg.jar%23200!/:?] {re:classloading,re:mixin}
        at TRANSFORMER/[email protected]/net.minecraft.util.thread.BlockableEventLoop.doRunTask(BlockableEventLoop.java:148) ~[server-1.21.1-20240808.144430-srg.jar%23200!/:?] {re:mixin,pl:accesstransformer:B,re:computing_frames,pl:accesstransformer:B,re:classloading,pl:accesstransformer:B}
        at TRANSFORMER/[email protected]/net.minecraft.util.thread.ReentrantBlockableEventLoop.doRunTask(ReentrantBlockableEventLoop.java:23) ~[server-1.21.1-20240808.144430-srg.jar%23200!/:?] {re:mixin,re:computing_frames,re:classloading}
        at TRANSFORMER/[email protected]/net.minecraft.server.MinecraftServer.doRunTask(MinecraftServer.java:872) ~[server-1.21.1-20240808.144430-srg.jar%23200!/:?] {re:mixin,pl:accesstransformer:B,re:classloading,pl:accesstransformer:B,pl:mixin:APP:aether.mixins.json:common.accessor.MinecraftServerAccessor from mod aether,pl:mixin:APP:balm.neoforge.mixins.json:MinecraftServerMixin from mod balm,pl:mixin:APP:enderscape.mixins.json:MinecraftServerMixin from mod enderscape,pl:mixin:APP:ponder-common.mixins.json:accessor.MinecraftServerAccessor from mod ponder,pl:mixin:A}
        at TRANSFORMER/[email protected]/net.minecraft.server.MinecraftServer.doRunTask(MinecraftServer.java:170) ~[server-1.21.1-20240808.144430-srg.jar%23200!/:?] {re:mixin,pl:accesstransformer:B,re:classloading,pl:accesstransformer:B,pl:mixin:APP:aether.mixins.json:common.accessor.MinecraftServerAccessor from mod aether,pl:mixin:APP:balm.neoforge.mixins.json:MinecraftServerMixin from mod balm,pl:mixin:APP:enderscape.mixins.json:MinecraftServerMixin from mod enderscape,pl:mixin:APP:ponder-common.mixins.json:accessor.MinecraftServerAccessor from mod ponder,pl:mixin:A}
        at TRANSFORMER/[email protected]/net.minecraft.util.thread.BlockableEventLoop.pollTask(BlockableEventLoop.java:122) ~[server-1.21.1-20240808.144430-srg.jar%23200!/:?] {re:mixin,pl:accesstransformer:B,re:computing_frames,pl:accesstransformer:B,re:classloading,pl:accesstransformer:B}
        at TRANSFORMER/[email protected]/net.minecraft.server.MinecraftServer.pollTaskInternal(MinecraftServer.java:855) ~[server-1.21.1-20240808.144430-srg.jar%23200!/:?] {re:mixin,pl:accesstransformer:B,re:classloading,pl:accesstransformer:B,pl:mixin:APP:aether.mixins.json:common.accessor.MinecraftServerAccessor from mod aether,pl:mixin:APP:balm.neoforge.mixins.json:MinecraftServerMixin from mod balm,pl:mixin:APP:enderscape.mixins.json:MinecraftServerMixin from mod enderscape,pl:mixin:APP:ponder-common.mixins.json:accessor.MinecraftServerAccessor from mod ponder,pl:mixin:A}
        at TRANSFORMER/[email protected]/net.minecraft.server.MinecraftServer.pollTask(MinecraftServer.java:849) ~[server-1.21.1-20240808.144430-srg.jar%23200!/:?] {re:mixin,pl:accesstransformer:B,re:classloading,pl:accesstransformer:B,pl:mixin:APP:aether.mixins.json:common.accessor.MinecraftServerAccessor from mod aether,pl:mixin:APP:balm.neoforge.mixins.json:MinecraftServerMixin from mod balm,pl:mixin:APP:enderscape.mixins.json:MinecraftServerMixin from mod enderscape,pl:mixin:APP:ponder-common.mixins.json:accessor.MinecraftServerAccessor from mod ponder,pl:mixin:A}
        at TRANSFORMER/[email protected]/net.minecraft.util.thread.BlockableEventLoop.runAllTasks(BlockableEventLoop.java:111) ~[server-1.21.1-20240808.144430-srg.jar%23200!/:?] {re:mixin,pl:accesstransformer:B,re:computing_frames,pl:accesstransformer:B,re:classloading,pl:accesstransformer:B}
        at TRANSFORMER/[email protected]/net.minecraft.server.MinecraftServer.waitUntilNextTick(MinecraftServer.java:825) ~[server-1.21.1-20240808.144430-srg.jar%23200!/:?] {re:mixin,pl:accesstransformer:B,re:classloading,pl:accesstransformer:B,pl:mixin:APP:aether.mixins.json:common.accessor.MinecraftServerAccessor from mod aether,pl:mixin:APP:balm.neoforge.mixins.json:MinecraftServerMixin from mod balm,pl:mixin:APP:enderscape.mixins.json:MinecraftServerMixin from mod enderscape,pl:mixin:APP:ponder-common.mixins.json:accessor.MinecraftServerAccessor from mod ponder,pl:mixin:A}
        at TRANSFORMER/[email protected]/net.minecraft.server.MinecraftServer.runServer(MinecraftServer.java:712) ~[server-1.21.1-20240808.144430-srg.jar%23200!/:?] {re:mixin,pl:accesstransformer:B,re:classloading,pl:accesstransformer:B,pl:mixin:APP:aether.mixins.json:common.accessor.MinecraftServerAccessor from mod aether,pl:mixin:APP:balm.neoforge.mixins.json:MinecraftServerMixin from mod balm,pl:mixin:APP:enderscape.mixins.json:MinecraftServerMixin from mod enderscape,pl:mixin:APP:ponder-common.mixins.json:accessor.MinecraftServerAccessor from mod ponder,pl:mixin:A}
        at TRANSFORMER/[email protected]/net.minecraft.server.MinecraftServer.lambda$spin$2(MinecraftServer.java:267) ~[server-1.21.1-20240808.144430-srg.jar%23200!/:?] {re:mixin,pl:accesstransformer:B,re:classloading,pl:accesstransformer:B,pl:mixin:APP:aether.mixins.json:common.accessor.MinecraftServerAccessor from mod aether,pl:mixin:APP:balm.neoforge.mixins.json:MinecraftServerMixin from mod balm,pl:mixin:APP:enderscape.mixins.json:MinecraftServerMixin from mod enderscape,pl:mixin:APP:ponder-common.mixins.json:accessor.MinecraftServerAccessor from mod ponder,pl:mixin:A}
        at java.base/java.lang.Thread.run(Thread.java:1583) [?:?] {re:mixin}

Please Read and Confirm The Following

I have confirmed this bug can be replicated without the use of Optifine.
I have confirmed this bug is on the most recently supported version of Minecraft.
I have confirmed the details provided in this report are concise as possible and does not contain vague information (ie. Versions are properly recorded, answers to questions are clear).
I have confirmed this bug is unique and has not been reported already.
If playing on a modpack, I have reported this bug to their issue tracker already.
I have confirmed that I'm reporting a bug in The Aether I, not The Aether II.

bconlon1 · Answer 1 · 2025-09-22T14:42:24.000Z

Looks like an older bug I thought was fixed, weird that its popping up again.

marleyinbloom · Answer 2 · 2025-09-24T15:26:30.000Z

Is there something in particular we can do to avoid it until a fix is pushed?

bconlon1 · Answer 3 · 2025-09-24T16:18:54.000Z

Not sure yet, can you provide info on what versions the server is running of the same things specified for the client?

marleyinbloom · Answer 4 · 2025-09-24T17:34:49.000Z

Server and client are both Aether 1.21.1-1.5.9 NeoForge
The clients are NeoForge 21.1.201
The server is NeoForge 21.1.203

bconlon1 · Answer 5 · 2025-09-24T17:36:42.000Z

What happens if they update to 21.1.203?

marleyinbloom · Answer 6 · 2025-09-24T17:38:26.000Z

I will try that, I haven't found any real consistency to what triggers it so I'll update and if it persists I'll comment here about it

GreatSaltyLake · Answer 7 · 2025-09-29T12:29:35.000Z

Hi, adding that we started experiencing the same issue and research lead me here. It doesn't seem to happen until after quite awhile, 12-16 hours it seems. Clients and server are on NeoForge 21.1.209 , MC v1.21.1 as well. It is resolved with a restart but eventually comes back.

[28Sep2025 23:47:37.046] [Server thread/ERROR] [net.minecraft.network.protocol.game.ServerPacketListener/]: Failed to handle packet ServerboundSelectKnownPacks[knownPacks=[minecraft:core:1.21.1, minecraft:trade_rebalance:1.21.1, minecraft:bundle:1.21.1]], suppressing error
java.lang.IllegalArgumentException: Failed to serialize ResourceKey[aether:moa_type / aether:white]: Item must not be minecraft:air
	at TRANSFORMER/[email protected]/net.minecraft.core.RegistrySynchronization.lambda$packRegistry$1(RegistrySynchronization.java:39) ~[server-1.21.1-20240808.144430-srg.jar%23226!/:?]
	at MC-BOOTSTRAP/[email protected]/com.mojang.serialization.DataResult$Error.getOrThrow(DataResult.java:287) ~[datafixerupper-8.0.16.jar%23100!/:?]
	at TRANSFORMER/[email protected]/net.minecraft.core.RegistrySynchronization.lambda$packRegistry$2(RegistrySynchronization.java:39) ~[server-1.21.1-20240808.144430-srg.jar%23226!/:?]
	at MC-BOOTSTRAP/[email protected]/it.unimi.dsi.fastutil.objects.ObjectArrayList$Spliterator.forEachRemaining(ObjectArrayList.java:955) ~[fastutil-8.5.12.jar%23111!/:?]
	at java.base/java.util.stream.ReferencePipeline$Head.forEach(ReferencePipeline.java:762) ~[?:?]
	at TRANSFORMER/[email protected]/net.minecraft.core.RegistrySynchronization.lambda$packRegistry$3(RegistrySynchronization.java:33) ~[server-1.21.1-20240808.144430-srg.jar%23226!/:?]
	at java.base/java.util.Optional.ifPresent(Optional.java:178) ~[?:?]
	at TRANSFORMER/[email protected]/net.minecraft.core.RegistrySynchronization.packRegistry(RegistrySynchronization.java:30) ~[server-1.21.1-20240808.144430-srg.jar%23226!/:?]
	at TRANSFORMER/[email protected]/net.minecraft.core.RegistrySynchronization.lambda$packRegistries$0(RegistrySynchronization.java:26) ~[server-1.21.1-20240808.144430-srg.jar%23226!/:?]
	at java.base/java.util.ArrayList.forEach(ArrayList.java:1596) ~[?:?]
	at java.base/java.util.Collections$UnmodifiableCollection.forEach(Collections.java:1117) ~[?:?]
	at TRANSFORMER/[email protected]/net.minecraft.core.RegistrySynchronization.packRegistries(RegistrySynchronization.java:26) ~[server-1.21.1-20240808.144430-srg.jar%23226!/:?]
	at TRANSFORMER/[email protected]/net.minecraft.server.network.config.SynchronizeRegistriesTask.sendRegistries(SynchronizeRegistriesTask.java:38) ~[server-1.21.1-20240808.144430-srg.jar%23226!/:?]
	at TRANSFORMER/[email protected]/net.minecraft.server.network.config.SynchronizeRegistriesTask.handler$bko000$fabric_resource_loader_v0$onSelectKnownPacks(SynchronizeRegistriesTask.java:553) ~[server-1.21.1-20240808.144430-srg.jar%23226!/:?]
	at TRANSFORMER/[email protected]/net.minecraft.server.network.config.SynchronizeRegistriesTask.handleResponse(SynchronizeRegistriesTask.java) ~[server-1.21.1-20240808.144430-srg.jar%23226!/:?]
	at TRANSFORMER/[email protected]/net.minecraft.server.network.ServerConfigurationPacketListenerImpl.handleSelectKnownPacks(ServerConfigurationPacketListenerImpl.java:157) ~[server-1.21.1-20240808.144430-srg.jar%23226!/:?]
	at TRANSFORMER/[email protected]/net.minecraft.network.protocol.configuration.ServerboundSelectKnownPacks.handle(ServerboundSelectKnownPacks.java:23) ~[server-1.21.1-20240808.144430-srg.jar%23226!/:?]
	at TRANSFORMER/[email protected]/net.minecraft.network.protocol.configuration.ServerboundSelectKnownPacks.handle(ServerboundSelectKnownPacks.java:11) ~[server-1.21.1-20240808.144430-srg.jar%23226!/:?]
	at TRANSFORMER/[email protected]/net.minecraft.network.protocol.PacketUtils.lambda$ensureRunningOnSameThread$0(PacketUtils.java:27) ~[server-1.21.1-20240808.144430-srg.jar%23226!/:?]
	at TRANSFORMER/[email protected]/net.minecraft.server.TickTask.run(TickTask.java:18) ~[server-1.21.1-20240808.144430-srg.jar%23226!/:?]
	at TRANSFORMER/[email protected]/net.minecraft.util.thread.BlockableEventLoop.doRunTask(BlockableEventLoop.java:148) ~[server-1.21.1-20240808.144430-srg.jar%23226!/:?]
	at TRANSFORMER/[email protected]/net.minecraft.util.thread.ReentrantBlockableEventLoop.doRunTask(ReentrantBlockableEventLoop.java:23) ~[server-1.21.1-20240808.144430-srg.jar%23226!/:?]
	at TRANSFORMER/[email protected]/net.minecraft.server.MinecraftServer.doRunTask(MinecraftServer.java:872) ~[server-1.21.1-20240808.144430-srg.jar%23226!/:?]
	at TRANSFORMER/[email protected]/net.minecraft.server.MinecraftServer.doRunTask(MinecraftServer.java:170) ~[server-1.21.1-20240808.144430-srg.jar%23226!/:?]
	at TRANSFORMER/[email protected]/net.minecraft.util.thread.BlockableEventLoop.pollTask(BlockableEventLoop.java:122) ~[server-1.21.1-20240808.144430-srg.jar%23226!/:?]
	at TRANSFORMER/[email protected]/net.minecraft.server.MinecraftServer.pollTaskInternal(MinecraftServer.java:855) ~[server-1.21.1-20240808.144430-srg.jar%23226!/:?]
	at TRANSFORMER/[email protected]/net.minecraft.server.MinecraftServer.pollTask(MinecraftServer.java:849) ~[server-1.21.1-20240808.144430-srg.jar%23226!/:?]
	at TRANSFORMER/[email protected]/net.minecraft.util.thread.BlockableEventLoop.managedBlock(BlockableEventLoop.java:132) ~[server-1.21.1-20240808.144430-srg.jar%23226!/:?]
	at TRANSFORMER/[email protected]/net.minecraft.server.MinecraftServer.managedBlock(MinecraftServer.java:821) ~[server-1.21.1-20240808.144430-srg.jar%23226!/:?]
	at TRANSFORMER/[email protected]/net.minecraft.server.MinecraftServer.waitUntilNextTick(MinecraftServer.java:826) ~[server-1.21.1-20240808.144430-srg.jar%23226!/:?]
	at TRANSFORMER/[email protected]/net.minecraft.server.MinecraftServer.runServer(MinecraftServer.java:712) ~[server-1.21.1-20240808.144430-srg.jar%23226!/:?]
	at TRANSFORMER/[email protected]/net.minecraft.server.MinecraftServer.lambda$spin$2(MinecraftServer.java:267) ~[server-1.21.1-20240808.144430-srg.jar%23226!/:?]
	at java.base/java.lang.Thread.run(Thread.java:1583) [?:?]

Part of the issue appears to be that Moa's are laying 64 eggs at a time occasionally? This is user reported; however, there were logs throwing a fit about 128 size stacks. I cant seem to locate this log now as the logs have been completely obliterated by the above logs; however, if I find it I will post it here.

ciekals11 · Answer 8 · 2025-10-01T17:52:30.000Z

Can confirm exact same error. One player on my smp incubated black moa and from this point after few hours after server restart no one is able to join and logs show exact error provided by @GreatSaltyLake

Server started at 17:09:30 and players were unable to join at 19:18:47 so almost exactly 2h
Previous successful join was at 18:11:12 so somewhere in that time frame

I have tried to remove this moa (and it's eggs) with commands
/kill @e[type=aether:moa]
and
/kill @e[type=#aether_black_moa_egg]
but neither of them found anything that matched.
No one knows where this moa is if it didn't despawned already

Minecraft 1.21.1
Neoforge 21.1.209
The Aether 1.21.1-1.5.10-neoforge
Deep Aether 1.21.1-1.1.4 (dunno if relevant)

GreatSaltyLake · Answer 9 · 2025-10-02T03:33:22.000Z

We were on Aether 1.5.9; however, moved to 1.5.10 and the error is continuing for a quick update. I self host and have 20G of RAM so it thankfully doesn't get too bad before our daily restarts but if players are exploring it seems to pop up much quicker.

bconlon1 · Answer 10 · 2025-10-02T03:36:46.000Z

@GreatSaltyLake do you have any other mods like the other users in the thread? I still have not been able to get to the bottom of the cause here.

GreatSaltyLake · Answer 11 · 2025-10-02T05:26:22.000Z

@bconlon1 Ya, here's our full list with versions to help correlate with others.

.connector
Ability Upgrade - Cobblemon [1.2]
Accelerated Decay [21.0.0]
Aether Villages [1.0.8]
Aethers Delight [0.1.4.1-1.21.1]
Architectury [13.0.8]
Artifacts [13.0.7]
Athena [4.0.2]
Autochef's Delight [2.0.2+neoforge]
BaguetteLib [1.1.1]
Balm [21.0.51]
Beltborne Lanterns [1.2.1]
Berry Pouch [0.4.2-beta]
Better Clouds [1.7.17+1.21.1-neoforge]
Better Third Person [1.9.0]
Caelus API [7.0.1+1.21.1]
Carry On [2.2.2]
Charm of Undying [9.1.0+1.21.1]
Chefs Delight [1.0.4]
Cloth Config v15 API [15.0.140]
CobbleFurnies [0.6.3]
Cobbled Armor Trims - Cobblemon [2.0]
Cobblemon [1.6.1+1.21.1]
Cobblemon Capture XP [1.6.1-neoforge-1.2.1]
Cobblemon Counter [1.6-neoforge-1.5.1]
CobblemonIntegrations [1.1.3]
Cobblemon Move Inspector [1.2.0]
Options Con Tim [1.6.1-neoforge-1.1.0]
Cobblemon Pokemon Badges [0.1.1]
Cobblenav [2.2.3]
Tim Core [1.6.1-neoforge-1.9.1]
Cobblemon Trainer Doubles [1.0]
Cobblemon Unchained [1.6-neoforge-1.3.0]
cobblemon_industries [1.2.4]
Cobblemon: Legends Untold [2.2]
Cobblemon: Mega Showdown [10.0.8-release-neoforge]
Cobblemon: Parting Gifts [3.0.0]
Cobblemon: Ride On! [0.3.3+1.21.1]
Cobblemore Library [1.1.1]
Cobbreeding [1.9.1]
Comforts [9.0.4+1.21.1]
Connector Extras [1.12.1+1.21.1]
Continuity [3.0.0+1.21.neoforge]
Controlling [19.0.5]
Corpse [1.21.1-1.1.13]
Corpse Curios Compatibility [3.1.2]
CraftTweaker [21.0.34]
CraftTweaker GUI [0.3.0]
CraterLib [2.1.5]
Create [6.0.6]
Create Crafts & Additions [1.5.3]
Create Encased [1.7.2-fix1]
Create Railways Navigator [1.21.1-beta-0.8.4]
Create Stuff & Additions [2.0.9]
Create: Bells & Whistles [0.4.7-1.21.1]
Create: Central Kitchen [2.2.3b]
Create: Copycats+ [3.0.2+mc.1.21.1-neoforge]
Create: Dragons Plus [1.8.0b]
Create: Enchantment Industry [2.2.2b]
Create Let The Adventure Begin [3.3.0]
Create: New Additional Recipes [0.0.3]
Create: Oxidized [0.1.3]
Create: Stam1o Tweaks [1.0.8]
Storage Drawers Create compat [1.0.1]
CreativeCore [2.13.13]
Cristel Lib [1.2.8]
Cumulus [2.0.7]
Curios API [9.5.1+1.21.1]
Deeper and Darker [1.3.4]
Default Options [21.1.5]
EasyItemList [0.1.4-1.20.5]
Elytra Slot [9.0.2+1.21.1]
Exposure [1.9.10]
Farmer's Delight [1.2.9]
Ferrite Core [7.0.2]
Forge Config API Port [21.1.4]
Forgified Fabric API [0.115.6+2.1.3+1.21.1]
Fzzy Config [0.7.2+1.21+neoforge]
GeckoLib 4 [4.8.2]
GuideME [21.1.14]
Iris [1.8.12-snapshot+mc1.21.1-local]
Jade [15.10.3+neoforge]
Just Enough Items [19.25.0.319]
Just Enough Resources [1.6.0.17]
Konkrete [1.9.9]
Kotlin for Forge [pp2cY80Q]
KubeJS [2101.7.1-build.181]
Lithium [0.15.0+mc1.21.1]
Lithostitched [1.5.0+beta4]
Lootr [1.21-1.10.35.91]
MaFgLib [0.4.1+mc1.21.1]
McMouser [1.0.0]
MidnightLib [1.7.5]
MoreMouseTweaks [1.1.1+1.21.1]
MoreCobblemonTweaks [1.1.4]
Mouse Tweaks [2.26.1]
No Creeper Grief [1-v.1.1.0]
No Enderman Grief [1-v.2.1.2]
Ok Zoomer [10.0.0-beta.10]
Particle Core [0.2.6+1.21+neoforge]
Platform [1.2.10.2]
Radical Cobblemon Trainers [0.16.8-beta]
Radical Cobblemon Trainers API [0.13.8-beta]
Reese's Sodium Options [1.8.3+mc1.21.4]
Rhino [2101.2.7-build.77]
Searchables [1.0.2]
Shorkie [2101.1.0.2]
Simple Discord Link [3.3.3]
Simple Voice Chat [1.21.1-2.6.4]
SimpleTMs [2.1.2]
Sinytra Connector [leZwcwvX]
Sodium [0.6.13+mc1.21.1]
Sodium Dynamic Lights [1.0.9]
Sodium Extra [0.6.0+mc1.21.1]
Sodium Leaf Culling [1.0.1]
Sodium Options API [1.0.10]
Sophisticated Backpacks [3.25.6]
Sophisticated Backpacks Create Integration [0.1.3]
Sophisticated Core [1.3.74]
Sophisticated Storage [1.5.6]
Sophisticated Storage Create Integration [0.1.11]
Storage Drawers [13.11.4]
TSFlareon's Item Core [1.0.0]
Tectonic [3.0.12]
The Aether [1.5.10]
Tomtaru's Cobblemon & Farmer's Delight Tweaks [1.3.0]
Tweakerge [0.3.2-mc1.21.1]
VanillaBackport [1.1.4.3]
Waystones [21.1.23]
Xaero's Minimap [25.2.10]
Xaero's World Map [1.39.12]
YetAnotherConfigLib [3.7.1+1.21.1-neoforge]
Entity Model Features [3.0.1]
Entity Texture Features [7.0.2]
ctgui-neoforge-1.21.1-0.3.0.jar.duplicate
oωo [0.12.15.5-beta.1+1.21]

rinebergc · Answer 12 · 2025-10-10T05:35:09.000Z

@bconlon1 looks like these are the mods @GreatSaltyLake and I have in common between our two packs - marked which seem not to be required/do anything on their own as well

NeoForge 21.1.209
Minecraft 1.21.1

Name	Version(s)	Note(s)
[EMF] Entity Model Features	`3.0.1`	Unused Dependency
[ETF] Entity Texture Features	`7.0.2`	Unused Dependency
Athena	`4.0.2`	Unused Dependency
Autochef's Delight	`2.0.2+neoforge`
Balm	`21.0.51` / `21.0.52`	Unused Dependency
Caelus API	`7.0.1+1.21.1`	Unused Dependency
Cloth Config API	`15.0.140`	Unused Dependency
Comforts	`9.0.4+1.21.1`
Create	`6.0.6`
CreativeCore	`2.13.13`	Unused Dependency
Curios API	`9.5.1+1.21.1`	Unused Dependency
Exposure	`1.9.10` / `1.9.11`
Farmer's Delight	`1.2.9`
FerriteCore	`7.0.2`
Forgified Fabric API	`0.115.6+2.1.3+1.21.1` / `0.115.6+2.1.4+1.21.1`	Unused Dependency
Fzzy Config	`0.7.2+1.21+neoforge`
Geckolib	`4.8.2`	Unused Dependency
Iris Shaders	`1.8.12-snapshot+mc1.21.1-local` / `1.8.12+1.21.1-neoforge`
Jade	`15.10.3+neoforge`
Kotlin for Forge	`5.10.0`
Lithium	`mc1.21.1-0.15.0-neoforge`
Lithostitched	`1.5.0+beta4` / `1.5.0`
Mouse Tweaks	`2.26.1`
owo-lib	`0.12.15.5-beta.1+1.21`
Particle Core	`0.2.6+1.21+neoforge`
Reese's Sodium Options	`1.8.3`
Sinytra Connector	`2.0.0-beta.9+1.21.1` / `2.0.0-beta.10+1.21.1`	Unused Dependency
Sodium	`0.6.13+mc1.21.1`
Sodium Extra	`0.6.0+mc1.21.1`
Sophisticated Backpacks	`3.25.6` / `3.25.9.1390`
Sophisticated Backpacks Create Integration	`0.1.3` / `0.1.4.23`
Sophisticated Core	`1.3.74` / `1.3.85.1219`
Tectonic	`2.4.3 / 3.0.12`
The Aether	`1.5.10`
Xaero's Minimap	`25.2.10`
Xaero's World Map	`1.39.12`
YetAnotherConfigLib	`3.7.1+1.21.1-neoforge`	Unused Dependency

rinebergc · Answer 13 · 2025-10-08T01:29:57.000Z

Encountering this bug as well. Error message almost identical to this comment, haven't seen or heard anything about excessively large clutches of eggs though.

Aether-specific info:

NeoForge 21.1.209
Minecraft 1.21.1
Aether Addon: Emissivity 1.21.1-1.0.2-neoforge
Aether Addon: Enhanced Extinguishing 1.21.1-1.0.0-neoforge
Aether Addon: Overworld Ores 1.21.1-1.0.2-neoforge
Aether Addon: Protect Your Moa 1.21.1-1.0.0-neoforge
Aether Addon: Treasure Reforging 1.21.1-1.0.1-neoforge
Explore Ruins: The Aether - Dungeons & Structures 1.0.0
Farmer's Cutting: The Aether 1.21.1-1.0-neoforge+mod
The Aether 1.21.1-1.5.10-neoforge

debug.log
full modlist

dninemfive · Answer 14 · 2025-10-16T14:23:11.000Z

i am also experiencing this issue. i'll compare my mod list with the two reported above to see if i can identify anything, but i'm seeing several overlaps already.

dninemfive · Answer 15 · 2025-10-16T15:36:17.000Z

i stuck @marleyinbloom and my modlists in a spreadsheet and added the overlaps from @rinebergc's comment above. Note that this spreadsheet does not have all of the mods @GreatSaltyLake and @rinebergc are using, as i was not able to extract the data from their logs like i was from @marleyinbloom's and my own.

This narrows down the mod overlaps considerably:

Mod ID	Mod Name	Version(s)
aether	The Aether	1.5.9, 1.5.10
balm	Balm	21.0.49, 21.0.51, 21.0.52, 21.0.54
cloth_config	Cloth Config API	15.0.140
create	Create	6.0.6
curios	Curios API	9.5.1+1.21.1
farmersdelight	Farmer's Delight	1.2.8, 1.2.9
ferritecore	Ferrite Core	7.0.2
fzzy_config	Fzzy Config	0.7.2+1.21+neoforge, 0.7.3+1.21+neoforge
geckolib	GeckoLib	4.7.7, 4.8.2
jade	Jade	15.10.3+neoforge
kotlinforforge	Kotlin For Forge	5.9.0, 5.10.0
lithium	Lithium	0.15.0+mc1.21.1
mousetweaks	Mouse Tweaks	2.26.1
owo	oωo	0.12.15.5-beta.1+1.21
reeses_sodium_options	Reese's Sodium Options	1.8.3+mc1.21.4, 1.8.3
sodium	Sodium	0.6.13+mc1.21.1
sophisticatedbackpacks	Sophisticated Backpacks	3.24.20, 3.25.6, 3.25.9.1390, 3.25.9
sophisticatedcore	Sophisticated Core	1.3.64, 1.3.74, 1.3.85.1219, 1.3.87
yet_another_config_lib_v3	YetAnotherConfigLib	3.7.1+1.21.1-neoforge

Note that none of these mods may cause the issue, given this comment above:

Looks like an older bug I thought was fixed, weird that its popping up again.

This data is just presented in case it helps.

Here are my debug.log and latest.log from just attempting to connect to the server. i've saved the relevant logs on the server side, too, but if you need those i'll need to go through to remove identifying information from the chat.

The stack trace on the server side was essentially identical to what was posted above:

java.lang.IllegalArgumentException: Failed to serialize ResourceKey[aether:moa_type / aether:blue]: Item must not be minecraft:air
	at TRANSFORMER/[email protected]/net.minecraft.core.RegistrySynchronization.lambda$packRegistry$1(RegistrySynchronization.java:39) ~[server-1.21.1-20240808.144430-srg.jar%23333!/:?]
	at MC-BOOTSTRAP/[email protected]/com.mojang.serialization.DataResult$Error.getOrThrow(DataResult.java:287) ~[datafixerupper-8.0.16.jar%23100!/:?]
	at TRANSFORMER/[email protected]/net.minecraft.core.RegistrySynchronization.lambda$packRegistry$2(RegistrySynchronization.java:39) ~[server-1.21.1-20240808.144430-srg.jar%23333!/:?]
	at MC-BOOTSTRAP/[email protected]/it.unimi.dsi.fastutil.objects.ObjectArrayList$Spliterator.forEachRemaining(ObjectArrayList.java:955) ~[fastutil-8.5.12.jar%23111!/:?]
	at java.base/java.util.stream.ReferencePipeline$Head.forEach(ReferencePipeline.java:762) ~[?:?]
	at TRANSFORMER/[email protected]/net.minecraft.core.RegistrySynchronization.lambda$packRegistry$3(RegistrySynchronization.java:33) ~[server-1.21.1-20240808.144430-srg.jar%23333!/:?]
	at java.base/java.util.Optional.ifPresent(Optional.java:178) ~[?:?]
	at TRANSFORMER/[email protected]/net.minecraft.core.RegistrySynchronization.packRegistry(RegistrySynchronization.java:30) ~[server-1.21.1-20240808.144430-srg.jar%23333!/:?]
	at TRANSFORMER/[email protected]/net.minecraft.core.RegistrySynchronization.lambda$packRegistries$0(RegistrySynchronization.java:26) ~[server-1.21.1-20240808.144430-srg.jar%23333!/:?]
	at java.base/java.util.ArrayList.forEach(ArrayList.java:1596) ~[?:?]
	at java.base/java.util.Collections$UnmodifiableCollection.forEach(Collections.java:1116) ~[?:?]
	at TRANSFORMER/[email protected]/net.minecraft.core.RegistrySynchronization.packRegistries(RegistrySynchronization.java:26) ~[server-1.21.1-20240808.144430-srg.jar%23333!/:?]
	at TRANSFORMER/[email protected]/net.minecraft.server.network.config.SynchronizeRegistriesTask.sendRegistries(SynchronizeRegistriesTask.java:38) ~[server-1.21.1-20240808.144430-srg.jar%23333!/:?]
	at TRANSFORMER/[email protected]/net.minecraft.server.network.config.SynchronizeRegistriesTask.handleResponse(SynchronizeRegistriesTask.java:51) ~[server-1.21.1-20240808.144430-srg.jar%23333!/:?]
	at TRANSFORMER/[email protected]/net.minecraft.server.network.ServerConfigurationPacketListenerImpl.handleSelectKnownPacks(ServerConfigurationPacketListenerImpl.java:157) ~[server-1.21.1-20240808.144430-srg.jar%23333!/:?]
	at TRANSFORMER/[email protected]/net.minecraft.network.protocol.configuration.ServerboundSelectKnownPacks.handle(ServerboundSelectKnownPacks.java:23) ~[server-1.21.1-20240808.144430-srg.jar%23333!/:?]
	at TRANSFORMER/[email protected]/net.minecraft.network.protocol.configuration.ServerboundSelectKnownPacks.handle(ServerboundSelectKnownPacks.java:11) ~[server-1.21.1-20240808.144430-srg.jar%23333!/:?]
	at TRANSFORMER/[email protected]/net.minecraft.network.protocol.PacketUtils.lambda$ensureRunningOnSameThread$0(PacketUtils.java:27) ~[server-1.21.1-20240808.144430-srg.jar%23333!/:?]
	at TRANSFORMER/[email protected]/net.minecraft.server.TickTask.run(TickTask.java:18) ~[server-1.21.1-20240808.144430-srg.jar%23333!/:?]
	at TRANSFORMER/[email protected]/net.minecraft.util.thread.BlockableEventLoop.doRunTask(BlockableEventLoop.java:148) ~[server-1.21.1-20240808.144430-srg.jar%23333!/:?]
	at TRANSFORMER/[email protected]/net.minecraft.util.thread.ReentrantBlockableEventLoop.doRunTask(ReentrantBlockableEventLoop.java:23) ~[server-1.21.1-20240808.144430-srg.jar%23333!/:?]
	at TRANSFORMER/[email protected]/net.minecraft.server.MinecraftServer.doRunTask(MinecraftServer.java:872) ~[server-1.21.1-20240808.144430-srg.jar%23333!/:?]
	at TRANSFORMER/[email protected]/net.minecraft.server.MinecraftServer.doRunTask(MinecraftServer.java:170) ~[server-1.21.1-20240808.144430-srg.jar%23333!/:?]
	at TRANSFORMER/[email protected]/net.minecraft.util.thread.BlockableEventLoop.pollTask(BlockableEventLoop.java:122) ~[server-1.21.1-20240808.144430-srg.jar%23333!/:?]
	at TRANSFORMER/[email protected]/net.minecraft.server.MinecraftServer.pollTaskInternal(MinecraftServer.java:855) ~[server-1.21.1-20240808.144430-srg.jar%23333!/:?]
	at TRANSFORMER/[email protected]/net.minecraft.server.MinecraftServer.pollTask(MinecraftServer.java:849) ~[server-1.21.1-20240808.144430-srg.jar%23333!/:?]
	at TRANSFORMER/[email protected]/net.minecraft.util.thread.BlockableEventLoop.managedBlock(BlockableEventLoop.java:132) ~[server-1.21.1-20240808.144430-srg.jar%23333!/:?]
	at TRANSFORMER/[email protected]/net.minecraft.server.MinecraftServer.managedBlock(MinecraftServer.java:821) ~[server-1.21.1-20240808.144430-srg.jar%23333!/:?]
	at TRANSFORMER/[email protected]/net.minecraft.server.MinecraftServer.waitUntilNextTick(MinecraftServer.java:826) ~[server-1.21.1-20240808.144430-srg.jar%23333!/:?]
	at TRANSFORMER/[email protected]/net.minecraft.server.MinecraftServer.runServer(MinecraftServer.java:712) ~[server-1.21.1-20240808.144430-srg.jar%23333!/:?]
	at TRANSFORMER/[email protected]/net.minecraft.server.MinecraftServer.lambda$spin$2(MinecraftServer.java:267) ~[server-1.21.1-20240808.144430-srg.jar%23333!/:?]
	at java.base/java.lang.Thread.run(Thread.java:1583) [?:?]

dninemfive · Answer 16 · 2025-10-16T17:21:58.000Z

For what it's worth, it seems that nobody has incubated any moas on our server, so the error is probably related to moa serialization in general rather than being related to incubated moas in particular.

darksonic300 · Answer 17 · 2025-10-29T10:53:49.000Z

Did any of you test this happening with The Aether only?

EliteScouter · Answer 18 · 2025-11-06T17:38:44.000Z

We are also having the issue on our server. Reboot is the only thing that fixes it.

https://mclo.gs/HD2cea6

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