Hello, I have an Aternos Server with Mohist as Software, when I join, this message keeps coming up in the chat and the console, the server is in 1.16.5 and ProtocolLib is in 4.7.0 with the Simple Chat Plugin

How do I fix this?

(This was taken from the server log)
[01:56:19] [Netty Epoll Server IO #2/ERROR] [Minecraft/]: [ProtocolLib] INTERNAL ERROR: Unable to intercept a read client packet.
4011 | If this problem hasn't already been reported, please open a ticket
4012 | at https://github.com/dmulloy2/ProtocolLib/issues with the following data:
4013 | Stack Trace:
4014 | java.lang.RuntimeException: Error occured while instancing generated class.
4015 | at com.comphenix.protocol.reflect.compiler.StructureCompiler.compile(StructureCompiler.java:249)
4016 | at com.comphenix.protocol.reflect.compiler.CompiledStructureModifier.withTarget(CompiledStructureModifier.java:132)
4017 | at com.comphenix.protocol.events.PacketContainer.(PacketContainer.java:139)
4018 | at com.comphenix.protocol.injector.netty.ProtocolInjector.onPacketReceiving(ProtocolInjector.java:324)
4019 | at com.comphenix.protocol.injector.netty.ChannelInjector.decode(ChannelInjector.java:593)
4020 | at io.netty.handler.codec.ByteToMessageDecoder.decodeRemovalReentryProtection(ByteToMessageDecoder.java:489)
4021 | at io.netty.handler.codec.ByteToMessageDecoder.callDecode(ByteToMessageDecoder.java:428)
4022 | at io.netty.handler.codec.ByteToMessageDecoder.channelRead(ByteToMessageDecoder.java:265)
4023 | at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:362)
4024 | at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:348)
4025 | at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:340)
4026 | at io.netty.handler.codec.ByteToMessageDecoder.fireChannelRead(ByteToMessageDecoder.java:310)
4027 | at io.netty.handler.codec.ByteToMessageDecoder.channelRead(ByteToMessageDecoder.java:284)
4028 | at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:362)
4029 | at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:348)
4030 | at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:340)
4031 | at com.comphenix.protocol.injector.netty.ChannelInjector$2.channelRead(ChannelInjector.java:289)
4032 | at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:362)
4033 | at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:348)
4034 | at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:340)
4035 | at io.netty.handler.codec.ByteToMessageDecoder.fireChannelRead(ByteToMessageDecoder.java:310)
4036 | at io.netty.handler.codec.ByteToMessageDecoder.channelRead(ByteToMessageDecoder.java:284)
4037 | at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:362)
4038 | at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:348)
4039 | at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:340)
4040 | at io.netty.handler.timeout.IdleStateHandler.channelRead(IdleStateHandler.java:286)
4041 | at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:362)
4042 | at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:348)
4043 | at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:340)
4044 | at io.netty.channel.DefaultChannelPipeline$HeadContext.channelRead(DefaultChannelPipeline.java:1434)
4045 | at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:362)
4046 | at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:348)
4047 | at io.netty.channel.DefaultChannelPipeline.fireChannelRead(DefaultChannelPipeline.java:965)
4048 | at io.netty.channel.epoll.AbstractEpollStreamChannel$EpollStreamUnsafe.epollInReady(AbstractEpollStreamChannel.java:808)
4049 | at io.netty.channel.epoll.EpollEventLoop.processReady(EpollEventLoop.java:408)
4050 | at io.netty.channel.epoll.EpollEventLoop.run(EpollEventLoop.java:308)
4051 | at io.netty.util.concurrent.SingleThreadEventExecutor$5.run(SingleThreadEventExecutor.java:884)
4052 | at java.base/java.lang.Thread.run(Thread.java:829)
4053 | Caused by: java.lang.reflect.InvocationTargetException
4054 | at jdk.internal.reflect.GeneratedConstructorAccessor67.newInstance(Unknown Source)
4055 | at java.base/jdk.internal.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
4056 | at java.base/java.lang.reflect.Constructor.newInstance(Constructor.java:490)
4057 | at com.comphenix.protocol.reflect.compiler.StructureCompiler.compile(StructureCompiler.java:233)
4058 | ... 37 more
4059 | Caused by: java.lang.NoClassDefFoundError: net/minecraft/server/v1_16_R3/PacketPlayInCustomPayload
4060 | at com.comphenix.protocol.reflect.compiler.CompiledStructure$net_minecraft_network_play_client_CCustomPayloadPacket$java_lang_Object.(Unknown Source)
4061 | ... 41 more
4062 | Dump:
4063 | Parameters:
4064 | io.netty.buffer.PooledUnsafeDirectByteBuf@b200f3c[
4065 | memoryAddress=140363675283472
4066 | recyclerHandle=io.netty.util.Recycler$DefaultHandle@6af588d9
4067 | chunk=Chunk(184e61c4: 2%, 286720/16777216)
4068 | handle=4611686018427389962
4069 | memory=java.nio.DirectByteBuffer[pos=0 lim=16777216 cap=16777216]
4070 | offset=81920
4071 | length=32
4072 | maxLength=32
4073 | cache=io.netty.buffer.PoolThreadCache@52e279ce
4074 | tmpNioBuf=
4075 | allocator=PooledByteBufAllocator(directByDefault: true)
4076 | refCnt=1
4077 | readerIndex=32
4078 | writerIndex=32
4079 | markedReaderIndex=0
4080 | markedWriterIndex=0
4081 | maxCapacity=2147483647
4082 | ]
4083 | manager:
4084 | com.comphenix.protocol.injector.PacketFilterManager@360d2f8e[
4085 | unhookTask=com.comphenix.protocol.injector.DelayedSingleTask@77600c88
4086 | packetListeners=[PacketAdapter[plugin=voicechat, sending=EMPTY_WHITELIST, receiving=ListeningWhitelist[priority=HIGHEST, packets=[START[class=PacketLoginInStart, id=0], CUSTOM_PAYLOAD[class=PacketLoginInCustomPayload, id=2], CUSTOM_PAYLOAD[class=PacketPlayInCustomPayload, id=10]], gamephase=PLAYING, options=[]]]]
4087 | packetInjector=com.comphenix.protocol.injector.netty.ProtocolInjector$5@73cb6760
4088 | playerInjection=com.comphenix.protocol.injector.netty.ProtocolInjector$4@1f2caf6b
4089 | inputBufferedPackets=[]
4090 | recievedListeners=com.comphenix.protocol.injector.SortedPacketListenerList@4002925f
4091 | sendingListeners=com.comphenix.protocol.injector.SortedPacketListenerList@3771c29b
4092 | hasClosed=false
4093 | classLoader=org.bukkit.plugin.java.PluginClassLoader@2eb3f735
4094 | reporter=com.comphenix.protocol.ProtocolLib$1@1fa94372
4095 | server=CraftServer{serverName=Mohist,serverVersion=1.16.5-907,minecraftVersion=1.16.5}
4096 | library=ProtocolLib v4.7.0
4097 | asyncFilterManager=com.comphenix.protocol.async.AsyncFilterManager@3140068e
4098 | knowsServerPackets=true
4099 | knowsClientPackets=true
4100 | phaseLoginCount=1
4101 | phasePlayingCount=2
4102 | packetCreation=true
4103 | nettyInjector=com.comphenix.protocol.injector.netty.ProtocolInjector@2e78b916
4104 | pluginVerifier=com.comphenix.protocol.injector.PluginVerifier@45769ea9
4105 | hasRecycleDistance=true
4106 | minecraftVersion=(MC: 1.16.5)
4107 | debug=false
4108 | ]
4109 | Sender:
4110 | com.comphenix.protocol.injector.netty.ChannelInjector@407436b5[
4111 | decodeBuffer=protected void net.minecraft.network.NettyPacketDecoder.decode(io.netty.channel.ChannelHandlerContext,io.netty.buffer.ByteBuf,java.util.List) throws java.lang.Exception
4112 | encodeBuffer=protected void net.minecraft.network.NettyPacketEncoder.encode(io.netty.channel.ChannelHandlerContext,java.lang.Object,io.netty.buffer.ByteBuf) throws java.lang.Exception
4113 | factory=com.comphenix.protocol.injector.netty.InjectionFactory@32fb33d2
4114 | player=CraftPlayer{name=CJRed}
4115 | updated=CraftPlayer{name=CJRed}
4116 | playerName=CJRed
4117 | playerConnection=net.minecraft.network.play.ServerPlayNetHandler@3c562891
4118 | networkManager=net.minecraft.network.NetworkManager@59209c92
4119 | originalChannel=[id: 0xaa1afcec, L:/172.20.0.28:44999 - R:/190.120.248.110:62463]
4120 | channelField=VolatileField [accessor=DefaultFieldAccessor [field=public io.netty.channel.Channel net.minecraft.network.NetworkManager.field_150746_k], container=net.minecraft.network.NetworkManager@59209c92, previous=[id: 0xaa1afcec, L:/172.20.0.28:44999 - R:/190.120.248.110:62463], current=com.comphenix.protocol.injector.netty.ChannelInjector$3@419f5ad9, previousLoaded=true, currentSet=true, forceAccess=true]
4121 | packetMarker={}
4122 | currentEvent=
4123 | finalEvent=
4124 | unfilteredProcessedPackets=com.comphenix.protocol.injector.netty.PacketFilterQueue@1c772f4a
4125 | vanillaDecoder=net.minecraft.network.NettyPacketDecoder@5cf6829c
4126 | vanillaEncoder=net.minecraft.network.NettyPacketEncoder@f1b8c5f
4127 | finishQueue=[]
4128 | channelListener=com.comphenix.protocol.injector.netty.ProtocolInjector@2e78b916
4129 | processor=com.comphenix.protocol.injector.NetworkProcessor@11c1224f
4130 | injected=true
4131 | closed=false
4132 | cumulation=PooledUnsafeDirectByteBuf(ridx: 32, widx: 32, cap: 32)
4133 | cumulator=io.netty.handler.codec.ByteToMessageDecoder$1@794bb089
4134 | singleDecode=false
4135 | decodeWasNull=false
4136 | first=true
4137 | decodeState=1
4138 | discardAfterReads=16
4139 | numReads=0
4140 | added=true
4141 | ]
4142 | Version:
4143 | ProtocolLib v4.7.0
4144 | Java Version:
4145 | 11.0.12
4146 | Server:
4147 | 1.16.5-907 (MC: 1.16.5)
4148

sorry if my english is bad

The official stance of ProtocolLib is to not use Mohist. They've done some shady stuff with plugin jars which you can read more about here: https://essentialsx.net/do-not-use-mohist.html