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 @7577278d
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@728babf3[
targetType=class net.minecraft.server.v1_16_R3.PacketPlayOutChat
target=
converter=
fieldType=class java.lang.Object
data=[private net.minecraft.server.v1_16_R3.IChatBaseComponent net.minecraft.server.v1_16_R3.PacketPlayOutChat.a, public net.kyori.adventure.text.Component net.minecraft.server.v1_16_R3.PacketPlayOutChat.adventure$message, public net.md_5.bungee.api.chat.BaseComponent[] net.minecraft.server.v1_16_R3.PacketPlayOutChat.components, private net.minecraft.server.v1_16_R3.ChatMessageType net.minecraft.server.v1_16_R3.PacketPlayOutChat.b, private java.util.UUID net.minecraft.server.v1_16_R3.PacketPlayOutChat.c]
defaultFields={public net.md_5.bungee.api.chat.BaseComponent[] net.minecraft.server.v1_16_R3.PacketPlayOutChat.components=2, private net.minecraft.server.v1_16_R3.ChatMessageType net.minecraft.server.v1_16_R3.PacketPlayOutChat.b=3, private java.util.UUID net.minecraft.server.v1_16_R3.PacketPlayOutChat.c=4}
subtypeCache={interface net.minecraft.server.v1_16_R3.IChatBaseComponent=StructureModifier[fieldType=interface net.minecraft.server.v1_16_R3.IChatBaseComponent, data=[private net.minecraft.server.v1_16_R3.IChatBaseComponent net.minecraft.server.v1_16_R3.PacketPlayOutChat.a]], class java.util.UUID=StructureModifier[fieldType=class java.util.UUID, data=[private java.util.UUID net.minecraft.server.v1_16_R3.PacketPlayOutChat.c]]}
customConvertHandling=false
useStructureCompiler=true
]
manager:
com.comphenix.protocol.injector.PacketFilterManager@21a923c7[
unhookTask=com.comphenix.protocol.injector.DelayedSingleTask@e52d032
packetListeners=[PacketAdapter[plugin=eco, sending=ListeningWhitelist[priority=NORMAL, packets=[WINDOW_ITEMS[class=PacketPlayOutWindowItems, id=19]], gamephase=PLAYING, options=[]], receiving=EMPTY_WHITELIST], PacketAdapter[plugin=eco, sending=ListeningWhitelist[priority=MONITOR, packets=[CHAT[class=PacketPlayOutChat, id=14]], gamephase=PLAYING, options=[]], receiving=EMPTY_WHITELIST], PacketAdapter[plugin=eco, sending=ListeningWhitelist[priority=MONITOR, packets=[OPEN_WINDOW_MERCHANT[class=PacketPlayOutOpenWindowMerchant, id=38]], gamephase=PLAYING, options=[]], receiving=EMPTY_WHITELIST], PacketAdapter[plugin=eco, sending=ListeningWhitelist[priority=NORMAL, packets=[AUTO_RECIPE[class=PacketPlayOutAutoRecipe, id=47]], gamephase=PLAYING, options=[]], receiving=EMPTY_WHITELIST], PacketAdapter[plugin=eco, sending=ListeningWhitelist[priority=NORMAL, packets=[SET_SLOT[class=PacketPlayOutSetSlot, id=21]], gamephase=PLAYING, options=[]], receiving=EMPTY_WHITELIST], PacketAdapter[plugin=eco, sending=EMPTY_WHITELIST, receiving=ListeningWhitelist[priority=NORMAL, packets=[SET_CREATIVE_SLOT[class=PacketPlayInSetCreativeSlot, id=40]], gamephase=PLAYING, options=[]]]]
packetInjector=com.comphenix.protocol.injector.netty.ProtocolInjector$5@63888a3
playerInjection=com.comphenix.protocol.injector.netty.ProtocolInjector$4@3e159190
inputBufferedPackets=[]
recievedListeners=com.comphenix.protocol.injector.SortedPacketListenerList@564a2a8e
sendingListeners=com.comphenix.protocol.injector.SortedPacketListenerList@4e81b335
hasClosed=false
classLoader=PluginClassLoader{plugin=ProtocolLib v4.6.0, pluginEnabled=true, url=plugins\ProtocolLib (4).jar}
reporter=com.comphenix.protocol.ProtocolLib$1@c3e57d6
server=CraftServer{serverName=Paper,serverVersion=git-Paper-777,minecraftVersion=1.16.5}
library=ProtocolLib v4.6.0
asyncFilterManager=com.comphenix.protocol.async.AsyncFilterManager@19ac99d2
knowsServerPackets=true
knowsClientPackets=true
phaseLoginCount=0
phasePlayingCount=6
packetCreation=false
nettyInjector=com.comphenix.protocol.injector.netty.ProtocolInjector@696515fd
pluginVerifier=com.comphenix.protocol.injector.PluginVerifier@fba60d9
hasRecycleDistance=true
minecraftVersion=(MC: 1.16.5)
debug=false
]
Sender:
com.comphenix.protocol.reflect.compiler.BackgroundCompiler@64f5004d[
listeners={com.comphenix.protocol.reflect.compiler.StructureCompiler$StructureKey@dc40f704=[com.comphenix.protocol.reflect.compiler.BackgroundCompiler$1@232d27ce], com.comphenix.protocol.reflect.compiler.StructureCompiler$StructureKey@384205d7=[com.comphenix.protocol.injector.StructureCache$1@62a604ab], com.comphenix.protocol.reflect.compiler.StructureCompiler$StructureKey@e933b7e4=[com.comphenix.protocol.reflect.compiler.BackgroundCompiler$1@3ec60c8e]}
listenerLock=java.lang.Object@727d9473
compiler=com.comphenix.protocol.reflect.compiler.StructureCompiler@38a4dea5
enabled=false
shuttingDown=false
executor=java.util.concurrent.Executors$FinalizableDelegatedExecutorService@6af51646
reporter=com.comphenix.protocol.ProtocolLib$1@c3e57d6
unknownPermGenBean=java.lang.Object@6459c5ea
permGenBean=
disablePermGenFraction=0.65
]
Version:
ProtocolLib v4.6.0
Java Version:
16.0.1
Server:
git-Paper-777 (MC: 1.16.5)

This is fixed in the latest dev builds. Find them here: https://ci.dmulloy2.net/job/ProtocolLib/