[06:01:11] [Server thread/INFO]: [ProtocolLib] Started structure compiler thread.
[06:01:11] [Server thread/ERROR]: [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.IllegalAccessError: tried to access class com.comphenix.protocol.injector.netty.ProtocolInjector$1 from class com.comphenix.protocol.injector.netty.ProtocolInjector
at com.comphenix.protocol.injector.netty.ProtocolInjector.inject(ProtocolInjector.java:144)
at com.comphenix.protocol.injector.PacketFilterManager.registerEvents(PacketFilterManager.java:887)
at com.comphenix.protocol.ProtocolLib.onEnable(ProtocolLib.java:387)
at org.bukkit.plugin.java.JavaPlugin.setEnabled(JavaPlugin.java:321)
at org.bukkit.plugin.java.JavaPluginLoader.enablePlugin(JavaPluginLoader.java:332)
at org.bukkit.plugin.SimplePluginManager.enablePlugin(SimplePluginManager.java:393)
at org.bukkit.craftbukkit.v1_8_R3.CraftServer.loadPlugin(CraftServer.java:382)
at org.bukkit.craftbukkit.v1_8_R3.CraftServer.enablePlugins(CraftServer.java:341)
at net.minecraft.server.v1_8_R3.DedicatedServer.init(DedicatedServer.java:208)
at net.minecraft.server.v1_8_R3.MinecraftServer.run(MinecraftServer.java:560)
at java.lang.Thread.run(Unknown Source)
Dump:
manager:
com.comphenix.protocol.injector.PacketFilterManager@28d40c51[
unhookTask=com.comphenix.protocol.injector.DelayedSingleTask@5c27b816
packetListeners=[]
packetInjector=com.comphenix.protocol.injector.netty.ProtocolInjector$5@25a5d283
playerInjection=com.comphenix.protocol.injector.netty.ProtocolInjector$4@398d4eb0
inputBufferedPackets=[]
recievedListeners=com.comphenix.protocol.injector.SortedPacketListenerList@31336b54
sendingListeners=com.comphenix.protocol.injector.SortedPacketListenerList@5035926c
hasClosed=false
classLoader=org.bukkit.plugin.java.PluginClassLoader@75965bd2
reporter=com.comphenix.protocol.ProtocolLib$1@5b0f6323
server=CraftServer{serverName=NachoSpigot,serverVersion=1.8.8,minecraftVersion=1.8.8}
library=ProtocolLib v4.6.0
asyncFilterManager=com.comphenix.protocol.async.AsyncFilterManager@2267eda7
knowsServerPackets=true
knowsClientPackets=true
phaseLoginCount=0
phasePlayingCount=0
packetCreation=false
nettyInjector=com.comphenix.protocol.injector.netty.ProtocolInjector@49e36a55
pluginVerifier=com.comphenix.protocol.injector.PluginVerifier@7a063019
hasRecycleDistance=true
minecraftVersion=(MC: 1.8.8)
debug=false
]
Sender:
com.comphenix.protocol.ProtocolLib@5a72e028[
statistics=
backgroundCompiler=com.comphenix.protocol.reflect.compiler.BackgroundCompiler@2b0a1528
packetTask=-1
tickCounter=0
unhookTask=com.comphenix.protocol.injector.DelayedSingleTask@5c27b816
configExpectedMod=-1
updater=com.comphenix.protocol.updater.SpigotUpdater@79e973de
redirectHandler=com.comphenix.protocol.ProtocolLib$2@32a41202
commandProtocol=com.comphenix.protocol.CommandProtocol@7f9ac7de
commandPacket=com.comphenix.protocol.CommandPacket@4c23e50
commandFilter=com.comphenix.protocol.CommandFilter@3607da95
packetLogging=com.comphenix.protocol.PacketLogging@2421ea55
skipDisable=false
isEnabled=true
loader=org.bukkit.plugin.java.JavaPluginLoader@10524085
server=CraftServer{serverName=NachoSpigot,serverVersion=1.8.8,minecraftVersion=1.8.8}
file=plugins\ProtocolLib (1).jar
description=org.bukkit.plugin.PluginDescriptionFile@3b0a7398
dataFolder=plugins\ProtocolLib
classLoader=org.bukkit.plugin.java.PluginClassLoader@75965bd2
naggable=true
ebean=
newConfig=YamlConfiguration[path='', root='YamlConfiguration']
configFile=plugins\ProtocolLib\config.yml
logger=org.bukkit.plugin.PluginLogger@2ecf6d1
]
Version:
ProtocolLib v4.6.0
Java Version:
1.8.0_231
Server:
1.8.8 (MC: 1.8.8)

[06:01:11] [Server thread/INFO]: [ProtocolLib] Disabling ProtocolLib v4.6.0

Duplicate of #1162

This issue was resolved in build 499+.

I use NachoSpigot. In this version, ProtocolLib does not work, but when running the normal spigot version, ProtocolLib is active

Ah, yeah, I see I replied too hastily and that this is a completely different issue. My apologies.

You might want to create an issue with NachoSpigot, because it seems like they hack around with the class that's causing an error a bit.

EDIT: Also, I cannot replicate the issue using either the latest release or the latest dev-build using either Java 8 or Java 15 on either Spigot or NachoSpigot. Have you tried rebuilding the latest version of NachoSpigot? It looks like a recent commit fixed some kind of issue with ProtocolLib. Perhaps it's the same issue?