Console kill mobs error

[2robie]

Hello, I have an error that appears in my console when I kill a mob. I'm in 1.20.4 on paper. Here is the error:

[23:37:12 WARN]: java.lang.RuntimeException: no class found: net.minecraft.world.item.component.CustomData
[23:37:12 WARN]:        at DropHeads_v3.9.10.jar//net.evmodder.EvLib.extras.ReflectionUtils.getRefClass(ReflectionUtils.java:99)
[23:37:12 WARN]:        at DropHeads_v3.9.10.jar//net.evmodder.EvLib.extras.NBTTagUtils.<clinit>(NBTTagUtils.java:39)
[23:37:12 WARN]:        at DropHeads_v3.9.10.jar//net.evmodder.DropHeads.JunkUtils.getDisplayName(JunkUtils.java:185)
[23:37:12 WARN]:        at DropHeads_v3.9.10.jar//net.evmodder.DropHeads.JunkUtils.getMurderItemComponent(JunkUtils.java:326)
[23:37:12 WARN]:        at DropHeads_v3.9.10.jar//net.evmodder.DropHeads.DropChanceAPI.getWeaponComponent(DropChanceAPI.java:573)
[23:37:12 WARN]:        at DropHeads_v3.9.10.jar//net.evmodder.DropHeads.DropChanceAPI.getBeheadMessage(DropChanceAPI.java:591)
[23:37:12 WARN]:        at DropHeads_v3.9.10.jar//net.evmodder.DropHeads.DropChanceAPI.triggerHeadDropEvent(DropChanceAPI.java:742)
[23:37:12 WARN]:        at DropHeads_v3.9.10.jar//net.evmodder.DropHeads.listeners.EntityDeathListener.onEntityDeath(EntityDeathListener.java:158)
[23:37:12 WARN]:        at DropHeads_v3.9.10.jar//net.evmodder.DropHeads.listeners.EntityDeathListener$DeathEventExecutor.execute(EntityDeathListener.java:293)
[23:37:12 WARN]:        at co.aikar.timings.TimedEventExecutor.execute(TimedEventExecutor.java:81)
[23:37:12 WARN]:        at org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.java:70)
[23:37:12 WARN]:        at io.papermc.paper.plugin.manager.PaperEventManager.callEvent(PaperEventManager.java:54)
[23:37:12 WARN]:        at io.papermc.paper.plugin.manager.PaperPluginManagerImpl.callEvent(PaperPluginManagerImpl.java:126)
[23:37:12 WARN]:        at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.java:615)
[23:37:12 WARN]:        at org.bukkit.craftbukkit.v1_20_R3.event.CraftEventFactory.callEntityDeathEvent(CraftEventFactory.java:987)
[23:37:12 WARN]:        at net.minecraft.world.entity.EntityLiving.dropAllDeathLoot(EntityLiving.java:1847)
[23:37:12 WARN]:        at net.minecraft.world.entity.EntityLiving.a(EntityLiving.java:1741)
[23:37:12 WARN]:        at net.minecraft.world.entity.EntityLiving.a(EntityLiving.java:1565)
[23:37:12 WARN]:        at net.minecraft.world.entity.animal.EntityAnimal.a(EntityAnimal.java:87)
[23:37:12 WARN]:        at net.minecraft.world.entity.player.EntityHuman.d(EntityHuman.java:1323)
[23:37:12 WARN]:        at net.minecraft.server.level.EntityPlayer.d(EntityPlayer.java:2283)
[23:37:12 WARN]:        at net.minecraft.server.network.PlayerConnection$3.a(PlayerConnection.java:2787)
[23:37:12 WARN]:        at net.minecraft.network.protocol.game.PacketPlayInUseEntity$1.a(PacketPlayInUseEntity.java:24)
[23:37:12 WARN]:        at net.minecraft.network.protocol.game.PacketPlayInUseEntity.a(PacketPlayInUseEntity.java:80)
[23:37:12 WARN]:        at net.minecraft.server.network.PlayerConnection.a(PlayerConnection.java:2711)
[23:37:12 WARN]:        at net.minecraft.network.protocol.game.PacketPlayInUseEntity.a(PacketPlayInUseEntity.java:67)
[23:37:12 WARN]:        at net.minecraft.network.protocol.game.PacketPlayInUseEntity.a(PacketPlayInUseEntity.java:12)
[23:37:12 WARN]:        at net.minecraft.network.protocol.PlayerConnectionUtils.lambda$ensureRunningOnSameThread$0(PlayerConnectionUtils.java:54)
[23:37:12 WARN]:        at net.minecraft.server.TickTask.run(TickTask.java:18)
[23:37:12 WARN]:        at net.minecraft.util.thread.IAsyncTaskHandler.d(IAsyncTaskHandler.java:149)
[23:37:12 WARN]:        at net.minecraft.util.thread.IAsyncTaskHandlerReentrant.d(IAsyncTaskHandlerReentrant.java:24)
[23:37:12 WARN]:        at net.minecraft.server.MinecraftServer.b(MinecraftServer.java:1465)
[23:37:12 WARN]:        at net.minecraft.server.MinecraftServer.d(MinecraftServer.java:194)
[23:37:12 WARN]:        at net.minecraft.util.thread.IAsyncTaskHandler.x(IAsyncTaskHandler.java:123)
[23:37:12 WARN]:        at net.minecraft.server.MinecraftServer.bl(MinecraftServer.java:1442)
[23:37:12 WARN]:        at net.minecraft.server.MinecraftServer.x(MinecraftServer.java:1365)
[23:37:12 WARN]:        at net.minecraft.util.thread.IAsyncTaskHandler.bu(IAsyncTaskHandler.java:112)
[23:37:12 WARN]:        at net.minecraft.server.MinecraftServer.a(MinecraftServer.java:1557)
[23:37:12 WARN]:        at net.minecraft.server.MinecraftServer.w(MinecraftServer.java:1226)
[23:37:12 WARN]:        at net.minecraft.server.MinecraftServer.lambda$spin$0(MinecraftServer.java:319)
[23:37:12 WARN]:        at java.base/java.lang.Thread.run(Thread.java:1583)
[23:37:12 WARN]: 
[23:37:12 WARN]: Found inconsistent skull meta, this should normally not happen and is not a Bukkit / Spigot issue, but one from a plugin you are using.
Bukkit will attempt to fix it this time for you, but may not be able to do this every time.
If you see this message after typing a command from a plugin, please report this to the plugin developer, they should use the api instead of relying on reflection (and doing it the wrong way).
[23:37:12 WARN]: Found inconsistent skull meta, this should normally not happen and is not a Bukkit / Spigot issue, but one from a plugin you are using.
Bukkit will attempt to fix it this time for you, but may not be able to do this every time.
If you see this message after typing a command from a plugin, please report this to the plugin developer, they should use the api instead of relying on reflection (and doing it the wrong way).

[EvModder]

Hmm, I probably broke something related to 1.20.4 when adding support for 1.21.4
I should be able to fix this pretty quickly (sorry for the slow reply on the bug report), but I recommend downgrading to a previous version of DropHeads in the meantime if you need to get it working