[03:39:01] [Server thread/ERROR] [Minecraft]: [ProtocolLib] INTERNAL ERROR: Cannot enable ProtocolLib.
If this problem hasn't already been reported, please open a ticket
at https://github.com/dmulloy2/ProtocolLib/issues with the following data:
Stack Trace:
java.lang.NoClassDefFoundError: com/comphenix/protocol/reflect/compiler/StructureCompiler
at com.comphenix.protocol.reflect.compiler.BackgroundCompiler.initializeCompiler(BackgroundCompiler.java:131)
at com.comphenix.protocol.reflect.compiler.BackgroundCompiler.(BackgroundCompiler.java:109)
at com.comphenix.protocol.ProtocolLib.onEnable(ProtocolLib.java:387)
at org.bukkit.plugin.java.JavaPlugin.setEnabled(JavaPlugin.java:159)
at org.bukkit.plugin.java.JavaPluginLoader.enablePlugin(JavaPluginLoader.java:324)
at org.bukkit.plugin.SimplePluginManager.enablePlugin(SimplePluginManager.java:408)
at org.bukkit.craftbukkit.v1_12_R1.CraftServer.enablePlugin(CraftServer.java:410)
at org.bukkit.craftbukkit.v1_12_R1.CraftServer.enablePlugins(CraftServer.java:349)
at net.minecraft.server.MinecraftServer.func_71247_a(MinecraftServer.java:352)
at net.minecraft.server.dedicated.DedicatedServer.func_71197_b(DedicatedServer.java:321)
at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:623)
at java.lang.Thread.run(Thread.java:750)
Caused by: java.lang.ClassNotFoundException: Failed to remap class com.comphenix.protocol.reflect.compiler.StructureCompiler
at org.bukkit.plugin.java.PluginClassLoader.remappedFindClass(PluginClassLoader.java:216)
at org.bukkit.plugin.java.PluginClassLoader.findClass(PluginClassLoader.java:141)
at org.bukkit.plugin.java.PluginClassLoader.findClass(PluginClassLoader.java:115)
at java.lang.ClassLoader.loadClass(ClassLoader.java:418)
at java.lang.ClassLoader.loadClass(ClassLoader.java:351)
... 12 more
Caused by: java.lang.NoClassDefFoundError: org/magmafoundation/magma/remapper/proxy/ProxyClassWriter
at org.magmafoundation.magma.remapper.remappers.ReflectionMethodRemapper.redirectVirtual(ReflectionMethodRemapper.java:150)
at org.magmafoundation.magma.remapper.remappers.ReflectionMethodRemapper.visitMethodInsn(ReflectionMethodRemapper.java:114)
at org.objectweb.asm.tree.MethodInsnNode.accept(Unknown Source)
at org.objectweb.asm.tree.InsnList.accept(Unknown Source)
at org.objectweb.asm.tree.MethodNode.accept(Unknown Source)
at org.objectweb.asm.tree.MethodNode.accept(Unknown Source)
at org.objectweb.asm.tree.ClassNode.accept(Unknown Source)
at org.magmafoundation.magma.remapper.utils.RemappingUtils.remapFindClass(RemappingUtils.java:113)
at org.bukkit.plugin.java.PluginClassLoader.remappedFindClass(PluginClassLoader.java:202)
... 16 more
Dump:
manager:
com.comphenix.protocol.injector.PacketFilterManager@de1b87e[
unhookTask=com.comphenix.protocol.injector.DelayedSingleTask@4db9c523
packetListeners=[]
packetInjector=com.comphenix.protocol.injector.netty.ProtocolInjector$5@3abda909
playerInjection=com.comphenix.protocol.injector.netty.ProtocolInjector$4@7f416fdb
interceptWritePacket=com.comphenix.protocol.injector.packet.InterceptWritePacket@7fe30a05
inputBufferedPackets=[]
recievedListeners=com.comphenix.protocol.injector.SortedPacketListenerList@7c705807
sendingListeners=com.comphenix.protocol.injector.SortedPacketListenerList@2bd25361
hasClosed=false
classLoader=org.bukkit.plugin.java.PluginClassLoader@5d5cacdb
reporter=com.comphenix.protocol.ProtocolLib$1@5f99ce77
server=CraftServer{serverName=Magma,serverVersion=1.12.2-15ea32c3,minecraftVersion=1.12.2}
library=ProtocolLib v4.4.0
asyncFilterManager=com.comphenix.protocol.async.AsyncFilterManager@460393dd
knowsServerPackets=true
knowsClientPackets=true
phaseLoginCount=0
phasePlayingCount=0
packetCreation=false
spigotInjector=
nettyInjector=com.comphenix.protocol.injector.netty.ProtocolInjector@66f542c6
pluginVerifier=com.comphenix.protocol.injector.PluginVerifier@52cc58e
hasRecycleDistance=true
minecraftVersion=(MC: 1.12.2)
loginPackets=com.comphenix.protocol.injector.LoginPackets@2b5cd1b9
debug=false
]
Sender:
com.comphenix.protocol.ProtocolLib@1c77affd[
statistics=
backgroundCompiler=
packetTask=-1
tickCounter=0
unhookTask=com.comphenix.protocol.injector.DelayedSingleTask@4db9c523
configExpectedMod=-1
updater=com.comphenix.protocol.updater.BukkitUpdater@c74a767
redirectHandler=com.comphenix.protocol.ProtocolLib$2@1fb9f89
commandProtocol=com.comphenix.protocol.CommandProtocol@5ba811e7
commandPacket=com.comphenix.protocol.CommandPacket@32990c6c
commandFilter=com.comphenix.protocol.CommandFilter@1bffdac7
packetLogging=com.comphenix.protocol.PacketLogging@46a509e6
skipDisable=false
isEnabled=true
loader=org.bukkit.plugin.java.JavaPluginLoader@5d990ffc
server=CraftServer{serverName=Magma,serverVersion=1.12.2-15ea32c3,minecraftVersion=1.12.2}
file=plugins/ProtocolLib.jar
description=org.bukkit.plugin.PluginDescriptionFile@2799924f
dataFolder=plugins/ProtocolLib
classLoader=org.bukkit.plugin.java.PluginClassLoader@5d5cacdb
naggable=true
newConfig=YamlConfiguration[path='', root='YamlConfiguration']
configFile=plugins/ProtocolLib/config.yml
logger=org.bukkit.plugin.PluginLogger@2cd1960c
]
Version:
ProtocolLib v4.4.0
Java Version:
1.8.0_362
Server:
1.12.2-15ea32c3 (MC: 1.12.2)
[03:39:01] [Server thread/INFO] [com.comphenix.protocol.ProtocolLib]: [ProtocolLib] Disabling ProtocolLib v4.4.0

I need help

ProtocolLib 4.4.0 ist already quite dated. Please try out Protocol Lib 5.0.0: https://github.com/dmulloy2/ProtocolLib/releases/tag/5.0.0