Full log:

---- Minecraft Crash Report ----
// I bet Cylons wouldn't have this problem.

Time: 2/9/21 2:31 PM
Description: Exception in server tick loop

java.lang.NoSuchMethodError: net.minecraft.entity.Entity.func_184215_y(Lnet/minecraft/entity/Entity;)Z
at com.legobmw99.allomancy.modules.powers.network.TryPushPullEntity.lambda$handle$0(TryPushPullEntity.java:57) ~[allomancy:4.3.0] {re:classloading}
at net.minecraftforge.fml.network.NetworkEvent$Context.enqueueWork(NetworkEvent.java:215) ~[forge:?] {re:classloading}
at com.legobmw99.allomancy.modules.powers.network.TryPushPullEntity.handle(TryPushPullEntity.java:45) ~[allomancy:4.3.0] {re:classloading}
at net.minecraftforge.fml.network.simple.IndexedMessageCodec.lambda$tryDecode$3(IndexedMessageCodec.java:128) ~[forge:?] {re:classloading}
at java.util.Optional.ifPresent(Optional.java:159) ~[?:1.8.0_211] {}
at net.minecraftforge.fml.network.simple.IndexedMessageCodec.tryDecode(IndexedMessageCodec.java:128) ~[forge:?] {re:classloading}
at net.minecraftforge.fml.network.simple.IndexedMessageCodec.consume(IndexedMessageCodec.java:162) ~[forge:?] {re:classloading}
at net.minecraftforge.fml.network.simple.SimpleChannel.networkEventListener(SimpleChannel.java:80) ~[forge:?] {re:classloading}
at net.minecraftforge.eventbus.EventBus.doCastFilter(EventBus.java:247) ~[eventbus-4.0.0.jar:?] {}
at net.minecraftforge.eventbus.EventBus.lambda$addListener$11(EventBus.java:239) ~[eventbus-4.0.0.jar:?] {}
at net.minecraftforge.eventbus.EventBus.post(EventBus.java:302) ~[eventbus-4.0.0.jar:?] {}
at net.minecraftforge.eventbus.EventBus.post(EventBus.java:283) ~[eventbus-4.0.0.jar:?] {}
at net.minecraftforge.fml.network.NetworkInstance.dispatch(NetworkInstance.java:84) ~[forge:?] {re:classloading}
at net.minecraftforge.fml.network.NetworkHooks.lambda$onCustomPayload$1(NetworkHooks.java:88) ~[forge:?] {re:classloading}
at java.util.Optional.map(Optional.java:215) ~[?:1.8.0_211] {}
at net.minecraftforge.fml.network.NetworkHooks.onCustomPayload(NetworkHooks.java:88) ~[forge:?] {re:classloading}
at net.minecraft.network.play.ServerPlayNetHandler.func_147349_a(ServerPlayNetHandler.java:1413) ~[?:?] {re:classloading}
at net.minecraft.network.play.client.CCustomPayloadPacket.func_148833_a(CCustomPayloadPacket.java:42) ~[?:?] {re:classloading,pl:runtimedistcleaner:A}
at net.minecraft.network.play.client.CCustomPayloadPacket.func_148833_a(CCustomPayloadPacket.java:12) ~[?:?] {re:classloading,pl:runtimedistcleaner:A}
at net.minecraft.network.PacketThreadUtil.func_225383_a(SourceFile:21) ~[?:?] {re:classloading}
at net.minecraft.util.concurrent.TickDelayedTask.run(SourceFile:18) ~[?:?] {re:classloading}
at net.minecraft.util.concurrent.ThreadTaskExecutor.func_213166_h(SourceFile:144) ~[?:?] {re:classloading,pl:accesstransformer:B}
at net.minecraft.util.concurrent.RecursiveEventLoop.func_213166_h(SourceFile:23) ~[?:?] {re:classloading}
at net.minecraft.server.MinecraftServer.func_213166_h(MinecraftServer.java:733) ~[?:?] {re:classloading,pl:accesstransformer:B,pl:runtimedistcleaner:A}
at net.minecraft.server.MinecraftServer.func_213166_h(MinecraftServer.java:159) ~[?:?] {re:classloading,pl:accesstransformer:B,pl:runtimedistcleaner:A}
at net.minecraft.util.concurrent.ThreadTaskExecutor.func_213168_p(SourceFile:118) ~[?:?] {re:classloading,pl:accesstransformer:B}
at net.minecraft.server.MinecraftServer.func_213205_aW(MinecraftServer.java:716) ~[?:?] {re:classloading,pl:accesstransformer:B,pl:runtimedistcleaner:A}
at net.minecraft.server.MinecraftServer.func_213168_p(MinecraftServer.java:710) ~[?:?] {re:classloading,pl:accesstransformer:B,pl:runtimedistcleaner:A}
at net.minecraft.util.concurrent.ThreadTaskExecutor.func_213160_bf(SourceFile:103) ~[?:?] {re:classloading,pl:accesstransformer:B}
at net.minecraft.server.MinecraftServer.func_213202_o(MinecraftServer.java:695) ~[?:?] {re:classloading,pl:accesstransformer:B,pl:runtimedistcleaner:A}
at net.minecraft.server.MinecraftServer.func_240802_v_(MinecraftServer.java:645) ~[?:?] {re:classloading,pl:accesstransformer:B,pl:runtimedistcleaner:A}
at net.minecraft.server.MinecraftServer.lambda$startServer$0(MinecraftServer.java:232) ~[?:?] {re:classloading,pl:accesstransformer:B,pl:runtimedistcleaner:A}
at java.lang.Thread.run(Thread.java:748) [?:1.8.0_211] {}

A detailed walkthrough of the error, its code path and all known details is as follows:

-- System Details --
Details:
Minecraft Version: 1.16.4
Minecraft Version ID: 1.16.4
Operating System: Linux (amd64) version 4.19-ovh-xxxx-std-ipv6-64
Java Version: 1.8.0_211, Oracle Corporation
Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
Memory: 1128686664 bytes (1076 MB) / 1884291072 bytes (1797 MB) up to 1908932608 bytes (1820 MB)
CPUs: 32
JVM Flags: 4 total; -Xmx2048M -Xms1024M -XX:ParallelGCThreads=2 -XX:ThreadStackSize=512
ModLauncher: 8.0.9+86+master.3cf110c
ModLauncher launch target: fmlserver
ModLauncher naming: srg

net.minecraft.entity.Entity.func_184215_y is net.minecraft.entity.Entity.isRidingOrBeingRiddenBy()

This method mustn't be called on the Server. It's marked as @onlyin(Dist.Client).