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Spawn C2ME Fix

Fixes chunk deadlock and game crash when using Spawn and C2ME together.
by Bramblejack
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2,886 downloads
0 likes
Updated Jul 6, 2026
0 hypes
Bug Fixes Utility & QoL

Description

This mod patches AnimalVariantManager.chooseWeightedVariant() in the Spawn mod to use the entity's own thread-safe RandomSource instead of Level.random.

This prevents a ConcurrentModificationException when C2ME calls finalizeSpawn from a worker thread during chunk generation, which would otherwise deadlock further chunk loading.

Known issues

The original approach was meant to make the animal variants deterministic, meaning you would always encounter the same variant in the same place in the world in the same seed. The fix breaks this behaviour and makes the variants completely random. Generating a world with the same seed will give you a different outcome each time.

There probably is a way to solve this more gracefully, but it would require much deeper integration which for me personally is out of scope.

spawn_c2me_fix-1.21.1-1.0.0.jar
MC Client, 1.21.1, NeoForge, Server
Release 2026-06-03 Get
spawn_c2me_fix-1.20.1-1.0.0.jar
MC Client, 1.20.1, Forge, Server
Release 2026-06-01 Get

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