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 (2).jar//com.comphenix.protocol.reflect.FuzzyReflection.getFieldByType(FuzzyReflection.java:397)
at ProtocolLib (2).jar//com.comphenix.protocol.reflect.accessors.Accessors.getFieldAccessor(Accessors.java:57)
at ProtocolLib (2).jar//com.comphenix.protocol.injector.netty.ChannelInjector.handleLogin(ChannelInjector.java:658)
at ProtocolLib (2).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.MessageToMessageDecoder.channelRead(MessageToMessageDecoder.java:103)
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 (2).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$2.run(ThreadExecutorMap.java:74)
at java.base/java.lang.Thread.run(Thread.java:833)
Dump:
Parameters:
io.netty.buffer.PooledUnsafeDirectByteBuf@39f2d127[
memoryAddress=140578373330640
recyclerHandle=io.netty.util.Recycler$DefaultHandle@65323061
chunk=Chunk(4af3378d: 29%, 1212416/4194304)
handle=2814779831877632
memory=java.nio.DirectByteBuffer[pos=0 lim=4194304 cap=4194304]
offset=40960
length=10
maxLength=16
cache=io.netty.buffer.PoolThreadCache@3eae7463
tmpNioBuf=
allocator=PooledByteBufAllocator(directByDefault: true)
refCnt=2
readerIndex=10
writerIndex=10
markedReaderIndex=0
markedWriterIndex=0
maxCapacity=2147483647
]
manager:
com.comphenix.protocol.injector.PacketFilterManager@315b5ed8[
unhookTask=com.comphenix.protocol.injector.DelayedSingleTask@9614f85
packetListeners=[]
packetInjector=com.comphenix.protocol.injector.netty.ProtocolInjector$5@7a90bb1b
playerInjection=com.comphenix.protocol.injector.netty.ProtocolInjector$4@71bc6da2
inputBufferedPackets=[]
recievedListeners=com.comphenix.protocol.injector.SortedPacketListenerList@1afa50d3
sendingListeners=com.comphenix.protocol.injector.SortedPacketListenerList@1964396e
hasClosed=false
classLoader=PluginClassLoader{plugin=ProtocolLib v4.8.0, pluginEnabled=true, url=plugins/ProtocolLib (2).jar}
reporter=com.comphenix.protocol.ProtocolLib$1@6653113a
server=CraftServer{serverName=Paper,serverVersion=git-Paper-215,minecraftVersion=1.19.2}
library=ProtocolLib v4.8.0
asyncFilterManager=com.comphenix.protocol.async.AsyncFilterManager@3c241bb6
knowsServerPackets=true
knowsClientPackets=true
phaseLoginCount=0
phasePlayingCount=0
packetCreation=false
nettyInjector=com.comphenix.protocol.injector.netty.ProtocolInjector@171aedbe
pluginVerifier=com.comphenix.protocol.injector.PluginVerifier@ce25e0a
hasRecycleDistance=true
minecraftVersion=(MC: 1.19.2)
debug=false
]
Sender:
com.comphenix.protocol.injector.netty.ChannelInjector@a82b406[
decodeBuffer=protected void net.minecraft.network.PacketDecoder.decode(io.netty.channel.ChannelHandlerContext,io.netty.buffer.ByteBuf,java.util.List) throws java.lang.Exception
encodeBuffer=protected void net.minecraft.network.PacketEncoder.encode(io.netty.channel.ChannelHandlerContext,java.lang.Object,io.netty.buffer.ByteBuf) throws java.lang.Exception
factory=com.comphenix.protocol.injector.netty.InjectionFactory@617fd24b
player=CraftPlayer{name=1_x409}
updated=
playerName=1_x409
playerConnection=
networkManager=net.minecraft.network.NetworkManager@212cc220
originalChannel=[id: 0x52668c61, L:/240.4.102.36:25575 - R:/240.4.92.62:49680]
channelField=VolatileField [accessor=DefaultFieldAccessor [field=public io.netty.channel.Channel net.minecraft.network.NetworkManager.m], container=net.minecraft.network.NetworkManager@212cc220, previous=[id: 0x52668c61, L:/240.4.102.36:25575 - R:/240.4.92.62:49680], current=com.comphenix.protocol.injector.netty.ChannelInjector$3@73510c05, previousLoaded=true, currentSet=true, forceAccess=true]
packetMarker={}
currentEvent=
finalEvent=
unfilteredProcessedPackets=com.comphenix.protocol.injector.netty.PacketFilterQueue@7702bb7
vanillaDecoder=net.minecraft.network.PacketDecoder@408ac4bb
vanillaEncoder=net.minecraft.network.PacketEncoder@49d7ff47
finishQueue=[]
channelListener=com.comphenix.protocol.injector.netty.ProtocolInjector@171aedbe
processor=com.comphenix.protocol.injector.NetworkProcessor@34b65b2b
injected=true
closed=false
cumulation=PooledUnsafeDirectByteBuf(ridx: 10, widx: 10, cap: 10)
cumulator=io.netty.handler.codec.ByteToMessageDecoder$1@bd3168b
singleDecode=false
first=true
firedChannelRead=false
selfFiredChannelRead=true
decodeState=1
discardAfterReads=16
numReads=0
added=true
]
Version:
ProtocolLib v4.8.0
Java Version:
17.0.1
Server:
git-Paper-215 (MC: 1.19.2)

Updating to latest fixed the error for me
https://ci.dmulloy2.net/job/ProtocolLib/lastSuccessfulBuild/