Version Info
v5.0.0-SNAPSHOT-b625
JDK 20
MC server core: PurPur 1.19.3-1993
Error (happens on server start):
[20:13:11] [Server thread/INFO]: [ProtocolLib] Loading server plugin ProtocolLib v5.0.0-SNAPSHOT-b625
[20:13:12] [Server thread/ERROR]: [ProtocolLib] Error initializing plugin 'ProtocolLib.jar' in folder 'plugins' (Is it up to date?)
java.lang.ExceptionInInitializerError: null
at com.comphenix.protocol.injector.netty.manager.NetworkManagerInjector.(NetworkManagerInjector.java:40) ~[ProtocolLib.jar:?]
at com.comphenix.protocol.injector.PacketFilterManager.(PacketFilterManager.java:108) ~[ProtocolLib.jar:?]
at com.comphenix.protocol.injector.PacketFilterBuilder.build(PacketFilterBuilder.java:120) ~[ProtocolLib.jar:?]
at com.comphenix.protocol.ProtocolLib.onLoad(ProtocolLib.java:175) ~[ProtocolLib.jar:?]
at io.papermc.paper.plugin.storage.ServerPluginProviderStorage.processProvided(ServerPluginProviderStorage.java:59) ~[purpur-1.19.3.jar:git-Purpur-1933]
at io.papermc.paper.plugin.storage.ServerPluginProviderStorage.processProvided(ServerPluginProviderStorage.java:18) ~[purpur-1.19.3.jar:git-Purpur-1933]
at io.papermc.paper.plugin.storage.SimpleProviderStorage.enter(SimpleProviderStorage.java:36) ~[purpur-1.19.3.jar:git-Purpur-1933]
at io.papermc.paper.plugin.entrypoint.LaunchEntryPointHandler.enter(LaunchEntryPointHandler.java:36) ~[purpur-1.19.3.jar:git-Purpur-1933]
at org.bukkit.craftbukkit.v1_19_R2.CraftServer.loadPlugins(CraftServer.java:442) ~[purpur-1.19.3.jar:git-Purpur-1933]
at net.minecraft.server.dedicated.DedicatedServer.initServer(DedicatedServer.java:309) ~[purpur-1.19.3.jar:git-Purpur-1933]
at net.minecraft.server.MinecraftServer.runServer(MinecraftServer.java:1117) ~[purpur-1.19.3.jar:git-Purpur-1933]
at net.minecraft.server.MinecraftServer.lambda$spin$0(MinecraftServer.java:321) ~[purpur-1.19.3.jar:git-Purpur-1933]
at java.lang.Thread.run(Thread.java:1623) ~[?:?]
Caused by: java.lang.UnsupportedOperationException: Cannot define class using reflection: Unable to make protected java.lang.Package java.lang.ClassLoader.getPackage(java.lang.String) accessible: module java.base does not "opens java.lang" to unnamed module @5dadcb6b
at com.comphenix.net.bytebuddy.dynamic.loading.ClassInjector$UsingReflection$Dispatcher$Initializable$Unavailable.defineClass(ClassInjector.java:472) ~[ProtocolLib.jar:?]
at com.comphenix.net.bytebuddy.dynamic.loading.ClassInjector$UsingReflection.injectRaw(ClassInjector.java:284) ~[ProtocolLib.jar:?]
at com.comphenix.net.bytebuddy.dynamic.loading.ClassInjector$AbstractBase.inject(ClassInjector.java:118) ~[ProtocolLib.jar:?]
at com.comphenix.net.bytebuddy.dynamic.loading.ClassLoadingStrategy$Default$InjectionDispatcher.load(ClassLoadingStrategy.java:241) ~[ProtocolLib.jar:?]
at com.comphenix.net.bytebuddy.dynamic.loading.ClassLoadingStrategy$Default.load(ClassLoadingStrategy.java:148) ~[ProtocolLib.jar:?]
at com.comphenix.net.bytebuddy.dynamic.TypeResolutionStrategy$Passive.initialize(TypeResolutionStrategy.java:101) ~[ProtocolLib.jar:?]
at com.comphenix.net.bytebuddy.dynamic.DynamicType$Default$Unloaded.load(DynamicType.java:6166) ~[ProtocolLib.jar:?]
at com.comphenix.protocol.injector.temporary.TemporaryPlayerFactory.setupProxyPlayerConstructor(TemporaryPlayerFactory.java:159) ~[ProtocolLib.jar:?]
at com.comphenix.protocol.injector.temporary.TemporaryPlayerFactory.(TemporaryPlayerFactory.java:47) ~[ProtocolLib.jar:?]

Java 17 working properly