Sign plugin broken?

On my Minecraft server, the sign plugin does not work!

In the console comes:

[17:08:08 INFO]: Nikrafter issued server command: / sign test

[17:08:08 ERROR]: zero

org.bukkit.command.CommandException: Unhandled exception executing command 'sign' in plugin SignPlugin v1.0

at org.bukkit.command.PluginCommand.execute (PluginCommand.java:46) ~ [patched_1.12.2.jar: git-Paper-1618]

at org.bukkit.command.SimpleCommandMap.dispatch (SimpleCommandMap.java:152) ~ [patched_1.12.2.jar: git-Paper-1618]

at org.bukkit.craftbukkit.v1_12_R1.CraftServer.dispatchCommand (CraftServer.java:685) ~ [patched_1.12.2.jar: git-Paper-1618]

at net.minecraft.server.v1_12_R1.PlayerConnection.handleCommand (PlayerConnection.java:1492) ~ [patched_1.12.2.jar: git-Paper-1618]

at net.minecraft.server.v1_12_R1.PlayerConnection.a (PlayerConnection.java:1297) ~ [patched_1.12.2.jar: git-Paper-1618]

at net.minecraft.server.v1_12_R1.PacketPlayInChat.a (PacketPlayInChat.java:45) ~ [patched_1.12.2.jar: git-Paper-1618]

at net.minecraft.server.v1_12_R1.PacketPlayInChat.a (PacketPlayInChat.java:5) ~ [patched_1.12.2.jar: git-Paper-1618]

at net.minecraft.server.v1_12_R1.PlayerConnectionUtils.lambda $ ensureMainThread $ 0 (PlayerConnectionUtils.java:14) ~ [patched_1.12.2.jar: git-Paper-1618]

at java.util.concurrent.Executors $ RunnableAdapter.call (Executors.java:511) ~ [?: 1.8.0_212]

at java.util.concurrent.FutureTask.run (FutureTask.java:266) ~ [?: 1.8.0_212]

at net.minecraft.server.v1_12_R1.SystemUtils.a (SourceFile: 46) ~ [patched_1.12.2.jar: git-Paper-1618]

at net.minecraft.server.v1_12_R1.MinecraftServer.D (MinecraftServer.java:850) ~ [patched_1.12.2.jar: git-Paper-1618]

at net.minecraft.server.v1_12_R1.DedicatedServer.D (DedicatedServer.java:423) ~ [patched_1.12.2.jar: git-Paper-1618]

at net.minecraft.server.v1_12_R1.MinecraftServer.C (MinecraftServer.java:774) ~ [patched_1.12.2.jar: git-Paper-1618]

at net.minecraft.server.v1_12_R1.MinecraftServer.run (MinecraftServer.java:666) ~ [patched_1.12.2.jar: git-Paper-1618]

at java.lang.Thread.run (Thread.java:748) [?: 1.8.0_212]

Caused by: java.lang.NoClassDefFoundError: org / bukkit / craftbukkit / v1_8_R3 / inventory / CraftItemStack

at de.pattyxdhd.sign.commands.SignCommand.onCommand (SignCommand.java:29) ~ [?:?]

at org.bukkit.command.PluginCommand.execute (PluginCommand.java:44) ~ [patched_1.12.2.jar: git-Paper-1618]

… 15 more

Caused by: java.lang.ClassNotFoundException: org.bukkit.craftbukkit.v1_8_R3.inventory.CraftItemStack

at org.bukkit.plugin.java.PluginClassLoader.findClass (PluginClassLoader.java:109) ~ [patched_1.12.2.jar: git-Paper-1618]

at org.bukkit.plugin.java.PluginClassLoader.findClass (PluginClassLoader.java:104) ~ [patched_1.12.2.jar: git-Paper-1618]

at java.lang.ClassLoader.loadClass (ClassLoader.java:424) ~ [?: 1.8.0_212]

at java.lang.ClassLoader.loadClass (ClassLoader.java:357) ~ [?: 1.8.0_212]

at de.pattyxdhd.sign.commands.SignCommand.onCommand (SignCommand.java:29) ~ [?:?]

at org.bukkit.command.PluginCommand.execute (PluginCommand.java:44) ~ [patched_1.12.2.jar: git-Paper-1618]

… 15 more

Caused by: java.lang.ClassNotFoundException:
org.bukkit.craftbukkit.v1_8_R3.inventory.CraftItemStack

I'm 90% sure that the library that the plugin was compiled with is different from the one you are using on the server.

EDIT: Now I'm 100% sure. Look here:

patched_1.12.2.jar: git-Paper-1618]

So you apparently use Paper Spigot in the 1.12.2 version.

The plugin was programmed for the v1_8_R3.

And how can I fix it?

I think you have to change the server version

Download the plugin that was programmed for the 1.12.2 version and not for the 1.8.

Either that or what I wrote xD

Maybe this is related to the fact that I use paper?

No it's the Minecraft version.

A plugin that has been programmed for 1.8 can't simply be used for the 1.12.2 version… At least not if resources> 1.8 come into play. Should actually be clear.

The error comes here:

at de.pattyxdhd.sign.commands.SignCommand.onCommand (SignCommand.java:29) ~ [?:?]

According to Github, this would be:

SignManager signManager = newSignManager (player.getItemInHand ());

So if you have an item in your hand that does not exist in 1.8, the error comes.

Ne you just use the wrong version you have 1.12.2 and the plugin is for 1.8 so either download the plugin that is for 1.12.2 or adjust your server version

More question marks don't make it better.

You either take a sign plugin that is for your version or you set your server to 1.8.

You could have linked the plugin in the post, because there's no "the sign plugin".

Works again