java.lang.RuntimeException: Error occured while instancing generated class.
at com.comphenix.protocol.reflect.compiler.StructureCompiler.compile(StructureCompiler.java:237)
at com.comphenix.protocol.reflect.compiler.CompiledStructureModifier.withTarget(CompiledStructureModifier.java:132)
at com.comphenix.protocol.events.PacketContainer.(PacketContainer.java:128)
at com.comphenix.protocol.injector.netty.ProtocolInjector.onPacketReceiving(ProtocolInjector.java:312)
at com.comphenix.protocol.injector.netty.ChannelInjector.decode(ChannelInjector.java:594)
at io.netty.handler.codec.ByteToMessageDecoder.decodeRemovalReentryProtection(ByteToMessageDecoder.java:489)
at io.netty.handler.codec.ByteToMessageDecoder.callDecode(ByteToMessageDecoder.java:428)
at io.netty.handler.codec.ByteToMessageDecoder.channelRead(ByteToMessageDecoder.java:265)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:362)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:348)
at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:340)
at io.netty.handler.codec.ByteToMessageDecoder.fireChannelRead(ByteToMessageDecoder.java:310)
at io.netty.handler.codec.ByteToMessageDecoder.channelRead(ByteToMessageDecoder.java:284)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:362)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:348)
at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:340)
at com.comphenix.protocol.injector.netty.ChannelInjector$2.channelRead(ChannelInjector.java:290)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:362)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:348)
at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:340)
at io.netty.handler.codec.ByteToMessageDecoder.fireChannelRead(ByteToMessageDecoder.java:310)
at io.netty.handler.codec.ByteToMessageDecoder.channelRead(ByteToMessageDecoder.java:284)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:362)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:348)
at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:340)
at io.netty.handler.timeout.IdleStateHandler.channelRead(IdleStateHandler.java:286)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:362)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:348)
at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:340)
at io.netty.channel.DefaultChannelPipeline$HeadContext.channelRead(DefaultChannelPipeline.java:1434)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:362)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:348)
at io.netty.channel.DefaultChannelPipeline.fireChannelRead(DefaultChannelPipeline.java:965)
at io.netty.channel.epoll.AbstractEpollStreamChannel$EpollStreamUnsafe.epollInReady(AbstractEpollStreamChannel.java:808)
at io.netty.channel.epoll.EpollEventLoop.processReady(EpollEventLoop.java:408)
at io.netty.channel.epoll.EpollEventLoop.run(EpollEventLoop.java:308)
at io.netty.util.concurrent.SingleThreadEventExecutor$5.run(SingleThreadEventExecutor.java:884)
at java.base/java.lang.Thread.run(Thread.java:834)
Caused by: java.lang.reflect.InvocationTargetException
at jdk.internal.reflect.GeneratedConstructorAccessor42.newInstance(Unknown Source)
at java.base/jdk.internal.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.base/java.lang.reflect.Constructor.newInstance(Constructor.java:490)
at com.comphenix.protocol.reflect.compiler.StructureCompiler.compile(StructureCompiler.java:221)
... 37 more
Caused by: java.lang.NoClassDefFoundError: net/minecraft/server/v1_16_R3/PacketPlayInFlying$PacketPlayInPosition
at com.comphenix.protocol.reflect.compiler.CompiledStructure$net_minecraft_network_play_client_CPlayerPacket_PositionPacket$java_lang_Object.(Unknown Source)
... 41 more
Dump:
Parameters:
io.netty.buffer.PooledUnsafeDirectByteBuf@23299957[
memoryAddress=140585704861712
recyclerHandle=io.netty.util.Recycler$DefaultHandle@4bfa79d9
chunk=Chunk(6ee5718d: 3%, 434176/16777216)
handle=4611686018427389953
memory=java.nio.DirectByteBuffer[pos=0 lim=16777216 cap=16777216]
offset=8192
length=26
maxLength=32
cache=io.netty.buffer.PoolThreadCache@5c3e1552
tmpNioBuf=
allocator=PooledByteBufAllocator(directByDefault: true)
refCnt=1
readerIndex=26
writerIndex=26
markedReaderIndex=0
markedWriterIndex=0
maxCapacity=2147483647
]
manager:
com.comphenix.protocol.injector.PacketFilterManager@3bfd1d1d[
unhookTask=com.comphenix.protocol.injector.DelayedSingleTask@25f44d54
packetListeners=[PacketAdapter[plugin=Themis, sending=EMPTY_WHITELIST, receiving=ListeningWhitelist[priority=NORMAL, packets=[POSITION[class=PacketPlayInPosition, id=18], POSITION_LOOK[class=PacketPlayInPositionLook, id=19], LOOK[class=PacketPlayInLook, id=20], FLYING[class=PacketPlayInFlying, id=21]], gamephase=PLAYING, options=[]]], PacketAdapter[plugin=Themis, sending=EMPTY_WHITELIST, receiving=ListeningWhitelist[priority=NORMAL, packets=[ABILITIES[class=PacketPlayInAbilities, id=26]], gamephase=PLAYING, options=[]]], PacketAdapter[plugin=Themis, sending=EMPTY_WHITELIST, receiving=ListeningWhitelist[priority=LOW, packets=[POSITION[class=PacketPlayInPosition, id=18], POSITION_LOOK[class=PacketPlayInPositionLook, id=19], LOOK[class=PacketPlayInLook, id=20], FLYING[class=PacketPlayInFlying, id=21]], gamephase=PLAYING, options=[]]], PacketAdapter[plugin=Themis, sending=ListeningWhitelist[priority=NORMAL, packets=[EXPLOSION[class=PacketPlayOutExplosion, id=27]], gamephase=PLAYING, options=[]], receiving=EMPTY_WHITELIST], PacketAdapter[plugin=Themis, sending=ListeningWhitelist[priority=NORMAL, packets=[KEEP_ALIVE[class=PacketPlayOutKeepAlive, id=31], KEEP_ALIVE[class=PacketPlayInKeepAlive, id=16]], gamephase=PLAYING, options=[]], receiving=ListeningWhitelist[priority=NORMAL, packets=[KEEP_ALIVE[class=PacketPlayOutKeepAlive, id=31], KEEP_ALIVE[class=PacketPlayInKeepAlive, id=16]], gamephase=PLAYING, options=[]]], PacketAdapter[plugin=AuthMe, sending=ListeningWhitelist[priority=NORMAL, packets=[WINDOW_ITEMS[class=PacketPlayOutWindowItems, id=19], SET_SLOT[class=PacketPlayOutSetSlot, id=21]], gamephase=PLAYING, options=[]], receiving=EMPTY_WHITELIST]]
packetInjector=com.comphenix.protocol.injector.netty.ProtocolInjector$5@6f00721e
playerInjection=com.comphenix.protocol.injector.netty.ProtocolInjector$4@3857f69a
inputBufferedPackets=[]
recievedListeners=com.comphenix.protocol.injector.SortedPacketListenerList@6b911178
sendingListeners=com.comphenix.protocol.injector.SortedPacketListenerList@6c087fb3
hasClosed=false
classLoader=org.bukkit.plugin.java.PluginClassLoader@67575fe
reporter=com.comphenix.protocol.ProtocolLib$1@790a50c
server=CraftServer{serverName=Mohist,serverVersion=unknown,minecraftVersion=1.16.5}
library=ProtocolLib v4.6.0
asyncFilterManager=com.comphenix.protocol.async.AsyncFilterManager@4bb3709e
knowsServerPackets=true
knowsClientPackets=true
phaseLoginCount=0
phasePlayingCount=7
packetCreation=false
nettyInjector=com.comphenix.protocol.injector.netty.ProtocolInjector@150887fa
pluginVerifier=com.comphenix.protocol.injector.PluginVerifier@75cb8e35
hasRecycleDistance=true
minecraftVersion=(MC: 1.16.5)
debug=false
]
Sender:
com.comphenix.protocol.injector.netty.ChannelInjector@54be6aad[
decodeBuffer=protected void net.minecraft.network.NettyPacketDecoder.decode(io.netty.channel.ChannelHandlerContext,io.netty.buffer.ByteBuf,java.util.List) throws java.lang.Exception
encodeBuffer=protected void net.minecraft.network.NettyPacketEncoder.encode(io.netty.channel.ChannelHandlerContext,java.lang.Object,io.netty.buffer.ByteBuf) throws java.lang.Exception
factory=com.comphenix.protocol.injector.netty.InjectionFactory@78f4ba4a
player=CraftPlayer{name=Abrar123456}
updated=CraftPlayer{name=Abrar123456}
playerName=Abrar123456
playerConnection=
networkManager=net.minecraft.network.NetworkManager@6901be54
originalChannel=[id: 0x717261f1, L:/172.18.0.232:25768 - R:/46.19.139.106:33174]
channelField=VolatileField [accessor=DefaultFieldAccessor [field=public io.netty.channel.Channel net.minecraft.network.NetworkManager.field_150746_k], container=net.minecraft.network.NetworkManager@6901be54, previous=[id: 0x717261f1, L:/172.18.0.232:25768 - R:/46.19.139.106:33174], current=com.comphenix.protocol.injector.netty.ChannelInjector$3@3694074c, previousLoaded=true, currentSet=true, forceAccess=true]
packetMarker={}
currentEvent=
finalEvent=
unfilteredProcessedPackets=com.comphenix.protocol.injector.netty.PacketFilterQueue@1aac0049
vanillaDecoder=net.minecraft.network.NettyPacketDecoder@3d60eab3
vanillaEncoder=net.minecraft.network.NettyPacketEncoder@da509a1
finishQueue=[]
channelListener=com.comphenix.protocol.injector.netty.ProtocolInjector@150887fa
processor=com.comphenix.protocol.injector.NetworkProcessor@61c9245c
injected=true
closed=false
cumulation=PooledUnsafeDirectByteBuf(ridx: 26, widx: 26, cap: 26)
cumulator=io.netty.handler.codec.ByteToMessageDecoder$1@121d4976
singleDecode=false
decodeWasNull=false
first=true
decodeState=1
discardAfterReads=16
numReads=0
added=true
]
Version:
ProtocolLib v4.6.0
Java Version:
11.0.9
Server:
unknown (MC: 1.16.5)

Which Bukkit derivative are you using? It says unknown