Stack Trace:
java.lang.reflect.InaccessibleObjectException: Unable to make protected final java.lang.Class java.lang.ClassLoader.defineClass(java.lang.String,byte[],int,int) throws java.lang.ClassFormatError accessible: module java.base does not "opens java.lang" to unnamed module @eba916f
at java.base/java.lang.reflect.AccessibleObject.checkCanSetAccessible(AccessibleObject.java:357)
at java.base/java.lang.reflect.AccessibleObject.checkCanSetAccessible(AccessibleObject.java:297)
at java.base/java.lang.reflect.Method.checkCanSetAccessible(Method.java:199)
at java.base/java.lang.reflect.Method.setAccessible(Method.java:193)
at com.comphenix.protocol.reflect.compiler.StructureCompiler.generateClass(StructureCompiler.java:299)
at com.comphenix.protocol.reflect.compiler.StructureCompiler.compile(StructureCompiler.java:213)
at com.comphenix.protocol.reflect.compiler.BackgroundCompiler$2.call(BackgroundCompiler.java:204)
at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)
at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1130)
at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:630)
at java.base/java.lang.Thread.run(Thread.java:831)
Dump:
Parameters:
com.comphenix.protocol.reflect.StructureModifier@36865193[
targetType=class net.minecraft.server.v1_16_R3.PacketPlayInBlockPlace
target=
converter=
fieldType=class java.lang.Object
data=[private net.minecraft.server.v1_16_R3.EnumHand net.minecraft.server.v1_16_R3.PacketPlayInBlockPlace.a, public long net.minecraft.server.v1_16_R3.PacketPlayInBlockPlace.timestamp]
defaultFields={private net.minecraft.server.v1_16_R3.EnumHand net.minecraft.server.v1_16_R3.PacketPlayInBlockPlace.a=0}
subtypeCache={}
customConvertHandling=false
useStructureCompiler=true
]
manager:
com.comphenix.protocol.injector.PacketFilterManager@548526c2[
unhookTask=com.comphenix.protocol.injector.DelayedSingleTask@50d80bef
packetListeners=[PacketAdapter[plugin=PlayerWarps, sending=EMPTY_WHITELIST, receiving=ListeningWhitelist[priority=NORMAL, packets=[UPDATE_SIGN[class=PacketPlayInUpdateSign, id=43]], gamephase=PLAYING, options=[]]], PacketAdapter[plugin=Spartan, sending=EMPTY_WHITELIST, receiving=ListeningWhitelist[priority=NORMAL, packets=[BLOCK_PLACE[class=PacketPlayInBlockPlace, id=47]], gamephase=PLAYING, options=[]]], PacketAdapter[plugin=VotingPlugin, sending=EMPTY_WHITELIST, receiving=ListeningWhitelist[priority=NORMAL, packets=[UPDATE_SIGN[class=PacketPlayInUpdateSign, id=43]], gamephase=PLAYING, options=[]]], PacketAdapter[plugin=HolographicDisplays, sending=ListeningWhitelist[priority=NORMAL, packets=[ENTITY_METADATA[class=PacketPlayOutEntityMetadata, id=68], REL_ENTITY_MOVE[class=PacketPlayOutRelEntityMove, id=39], REL_ENTITY_MOVE_LOOK[class=PacketPlayOutRelEntityMoveLook, id=40], SPAWN_ENTITY[class=PacketPlayOutSpawnEntity, id=0], SPAWN_ENTITY_LIVING[class=PacketPlayOutSpawnEntityLiving, id=2]], gamephase=PLAYING, options=[]], receiving=EMPTY_WHITELIST], PacketAdapter[plugin=Spartan, sending=ListeningWhitelist[priority=NORMAL, packets=[TRANSACTION[class=PacketPlayInTransaction, id=7], KEEP_ALIVE[class=PacketPlayOutKeepAlive, id=31], KEEP_ALIVE[class=PacketPlayInKeepAlive, id=16]], gamephase=PLAYING, options=[]], receiving=ListeningWhitelist[priority=NORMAL, packets=[TRANSACTION[class=PacketPlayInTransaction, id=7], KEEP_ALIVE[class=PacketPlayOutKeepAlive, id=31], KEEP_ALIVE[class=PacketPlayInKeepAlive, id=16]], gamephase=PLAYING, options=[]]], PacketAdapter[plugin=CMI, sending=ListeningWhitelist[priority=HIGH, packets=[UNLOAD_CHUNK[class=PacketPlayOutUnloadChunk, id=28]], gamephase=PLAYING, options=[]], receiving=EMPTY_WHITELIST]]
packetInjector=com.comphenix.protocol.injector.netty.ProtocolInjector$5@21ad6988
playerInjection=com.comphenix.protocol.injector.netty.ProtocolInjector$4@25a3bee7
inputBufferedPackets=[]
recievedListeners=com.comphenix.protocol.injector.SortedPacketListenerList@586d2fa7
sendingListeners=com.comphenix.protocol.injector.SortedPacketListenerList@48fac036
hasClosed=false
classLoader=PluginClassLoader{plugin=ProtocolLib v4.6.0, pluginEnabled=true, url=plugins/ProtocolLib.jar}
reporter=com.comphenix.protocol.ProtocolLib$1@2d11188
server=CraftServer{serverName=Paper,serverVersion=git-Paper-777,minecraftVersion=1.16.5}
library=ProtocolLib v4.6.0
asyncFilterManager=com.comphenix.protocol.async.AsyncFilterManager@b9cd344
knowsServerPackets=true
knowsClientPackets=true
phaseLoginCount=0
phasePlayingCount=8
packetCreation=true
nettyInjector=com.comphenix.protocol.injector.netty.ProtocolInjector@2631d3d6
pluginVerifier=com.comphenix.protocol.injector.PluginVerifier@795cb4b0
hasRecycleDistance=true
minecraftVersion=(MC: 1.16.5)
debug=false
]
Sender:
com.comphenix.protocol.reflect.compiler.BackgroundCompiler@14a7d2f3[
listeners={com.comphenix.protocol.reflect.compiler.StructureCompiler$StructureKey@dbbda27f=[com.comphenix.protocol.injector.StructureCache$1@e9f1d92]}
listenerLock=java.lang.Object@2698d0f4
compiler=com.comphenix.protocol.reflect.compiler.StructureCompiler@3a7d09a3
enabled=false
shuttingDown=false
executor=java.util.concurrent.Executors$FinalizableDelegatedExecutorService@10676455
reporter=com.comphenix.protocol.ProtocolLib$1@2d11188
unknownPermGenBean=java.lang.Object@66e28846
permGenBean=
disablePermGenFraction=0.65
]
Version:
ProtocolLib v4.6.0
Java Version:
16.0.1
Server:
git-Paper-777 (MC: 1.16.5)

This has already been fixed in 4.6.1.