Stack Trace:
java.lang.IllegalArgumentException: Unable to find a field null with the type com.mojang.authlib.GameProfile in net.minecraft.network.protocol.login.PacketLoginInStart
at ProtocolLib.jar//com.comphenix.protocol.reflect.FuzzyReflection.getFieldByType(FuzzyReflection.java:397)
at ProtocolLib.jar//com.comphenix.protocol.reflect.accessors.Accessors.getFieldAccessor(Accessors.java:57)
at ProtocolLib.jar//com.comphenix.protocol.injector.netty.ChannelInjector.handleLogin(ChannelInjector.java:658)
at ProtocolLib.jar//com.comphenix.protocol.injector.netty.ChannelInjector.decode(ChannelInjector.java:591)
at io.netty.handler.codec.ByteToMessageDecoder.decodeRemovalReentryProtection(ByteToMessageDecoder.java:510)
at io.netty.handler.codec.ByteToMessageDecoder.callDecode(ByteToMessageDecoder.java:449)
at io.netty.handler.codec.ByteToMessageDecoder.channelRead(ByteToMessageDecoder.java:279)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:379)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:365)
at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:357)
at io.netty.handler.codec.ByteToMessageDecoder.fireChannelRead(ByteToMessageDecoder.java:327)
at io.netty.handler.codec.ByteToMessageDecoder.channelRead(ByteToMessageDecoder.java:299)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:379)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:365)
at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:357)
at ProtocolLib.jar//com.comphenix.protocol.injector.netty.ChannelInjector$2.channelRead(ChannelInjector.java:292)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:379)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:365)
at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:357)
at io.netty.handler.codec.ByteToMessageDecoder.fireChannelRead(ByteToMessageDecoder.java:327)
at io.netty.handler.codec.ByteToMessageDecoder.channelRead(ByteToMessageDecoder.java:299)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:379)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:365)
at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:357)
at io.netty.handler.timeout.IdleStateHandler.channelRead(IdleStateHandler.java:286)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:379)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:365)
at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:357)
at io.netty.handler.flush.FlushConsolidationHandler.channelRead(FlushConsolidationHandler.java:152)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:379)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:365)
at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:357)
at io.netty.channel.DefaultChannelPipeline$HeadContext.channelRead(DefaultChannelPipeline.java:1410)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:379)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:365)
at io.netty.channel.DefaultChannelPipeline.fireChannelRead(DefaultChannelPipeline.java:919)
at io.netty.channel.epoll.AbstractEpollStreamChannel$EpollStreamUnsafe.epollInReady(AbstractEpollStreamChannel.java:800)
at io.netty.channel.epoll.EpollEventLoop.processReady(EpollEventLoop.java:487)
at io.netty.channel.epoll.EpollEventLoop.run(EpollEventLoop.java:385)
at io.netty.util.concurrent.SingleThreadEventExecutor$4.run(SingleThreadEventExecutor.java:995)
at io.netty.util.internal.ThreadExecutorMap$2.run(ThreadExecutorMap.java:74)
at java.base/java.lang.Thread.run(Thread.java:833)
Dump:
Parameters:
io.netty.buffer.PooledUnsafeDirectByteBuf@764c75ee[
memoryAddress=140653685848672
recyclerHandle=io.netty.util.Recycler$DefaultHandle@6265747e
chunk=Chunk(75e8ffe5: 22%, 917504/4194304)
handle=37154795710054401
memory=java.nio.DirectByteBuffer[pos=0 lim=4194304 cap=4194304]
offset=540832
length=137
maxLength=160
cache=io.netty.buffer.PoolThreadCache@4dbc7fc9
tmpNioBuf=
allocator=PooledByteBufAllocator(directByDefault: true)
refCnt=2
readerIndex=137
writerIndex=137
markedReaderIndex=0
markedWriterIndex=0
maxCapacity=2147483647
]
manager:
com.comphenix.protocol.injector.PacketFilterManager@5caa58aa[
unhookTask=com.comphenix.protocol.injector.DelayedSingleTask@17056a09
packetListeners=[]
packetInjector=com.comphenix.protocol.injector.netty.ProtocolInjector$5@598ddae2
playerInjection=com.comphenix.protocol.injector.netty.ProtocolInjector$4@c0ad9a5
inputBufferedPackets=[]
recievedListeners=com.comphenix.protocol.injector.SortedPacketListenerList@2ebbf86
sendingListeners=com.comphenix.protocol.injector.SortedPacketListenerList@3e02d8f0
hasClosed=false
classLoader=PluginClassLoader{plugin=ProtocolLib v4.8.0, pluginEnabled=true, url=plugins/ProtocolLib.jar}
reporter=com.comphenix.protocol.ProtocolLib$1@96f4f18
server=CraftServer{serverName=Paper,serverVersion=git-Paper-20,minecraftVersion=1.19}
library=ProtocolLib v4.8.0
asyncFilterManager=com.comphenix.protocol.async.AsyncFilterManager@c3aea16
knowsServerPackets=true
knowsClientPackets=true
phaseLoginCount=0
phasePlayingCount=0
packetCreation=false
nettyInjector=com.comphenix.protocol.injector.netty.ProtocolInjector@4c738377
pluginVerifier=com.comphenix.protocol.injector.PluginVerifier@538ac26e
hasRecycleDistance=true
minecraftVersion=(MC: 1.19.0)
debug=false
]
Sender:
com.comphenix.protocol.injector.netty.ChannelInjector@38389d5d[
decodeBuffer=protected void com.viaversion.viaversion.bukkit.handlers.BukkitDecodeHandler.decode(io.netty.channel.ChannelHandlerContext,io.netty.buffer.ByteBuf,java.util.List) throws java.lang.Exception
encodeBuffer=protected void com.viaversion.viaversion.bukkit.handlers.BukkitEncodeHandler.encode(io.netty.channel.ChannelHandlerContext,java.lang.Object,io.netty.buffer.ByteBuf) throws java.lang.Exception
factory=com.comphenix.protocol.injector.netty.InjectionFactory@4956d68e
player=CraftPlayer{name=PrinceTom}
updated=
playerName=PrinceTom
playerConnection=
networkManager=net.minecraft.network.NetworkManager@15d5252b
originalChannel=[id: 0xabed2860, L:/185.7.32.16:25965 - R:/185.7.32.16:34183]
channelField=VolatileField [accessor=DefaultFieldAccessor [field=public io.netty.channel.Channel net.minecraft.network.NetworkManager.m], container=net.minecraft.network.NetworkManager@15d5252b, previous=[id: 0xabed2860, L:/185.7.32.16:25965 - R:/185.7.32.16:34183], current=com.comphenix.protocol.injector.netty.ChannelInjector$3@44fbbd4e, previousLoaded=true, currentSet=true, forceAccess=true]
packetMarker={}
currentEvent=
finalEvent=
unfilteredProcessedPackets=com.comphenix.protocol.injector.netty.PacketFilterQueue@7f08124f
vanillaDecoder=com.viaversion.viaversion.bukkit.handlers.BukkitDecodeHandler@43c88cf8
vanillaEncoder=com.viaversion.viaversion.bukkit.handlers.BukkitEncodeHandler@53e65790
finishQueue=[]
channelListener=com.comphenix.protocol.injector.netty.ProtocolInjector@4c738377
processor=com.comphenix.protocol.injector.NetworkProcessor@754b6807
injected=true
closed=false
cumulation=PooledUnsafeDirectByteBuf(ridx: 137, widx: 137, cap: 137)
cumulator=io.netty.handler.codec.ByteToMessageDecoder$1@597f7842
singleDecode=false
first=true
firedChannelRead=false
selfFiredChannelRead=true
decodeState=1
discardAfterReads=16
numReads=0
added=true
]
Version:
ProtocolLib v4.8.0
Java Version:
18.0.1.1
Server:
git-Paper-20 (MC: 1.19)

is this on 1.19, because i have the same error

Wild guess, but this might be because ProtocolLib isn't supported on 1.19? The latest release' support goes up to 1.18.2.

i have exact same problem

i got the same issue

Guys, don't just keep commenting you have the same thing.
Either just react to the initial comment with 👍, or don't say anything and just Subscribe to the issue.

This is fixed in the latest dev builds. Please search through the open and closed issue before filing a new one the next time you think you found an issue. There are like 20 Issues with the same error already! Find the dev build here: https://ci.dmulloy2.net/job/ProtocolLib/

Thanks derklaro for sharing the solution: https://ci.dmulloy2.net/job/ProtocolLib/
Much appreciated!