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Tickwise
ErrorPluginsSIG-PL-005

Plugin incompatible with the server version (NoSuchMethodError/NoClassDefFoundError on API/NMS)

Platforms
Paper · Purpur · single server
Verified
Verified
Confidence
Confidence 90%

What it looks like in the log

Any one of these lines is enough. The agent matches them locally, on your server.

logs/latest.log
  • [WARN] java.lang.NoSuchMethodError: 'in the stack trace
  • [WARN] java.lang.NoSuchFieldError: Class in the stack trace
  • [WARN] java.lang.NoClassDefFoundError: in the stack trace
  • [WARN] java.lang.ClassNotFoundException: in the stack trace

Symptoms

  • The plugin does not enable, or its features fail with errors after a server update
  • In the trace: NoSuchMethodError/NoSuchFieldError/NoClassDefFoundError/ClassNotFoundException for net.minecraft or org.bukkit classes

Cause

The plugin calls a server method, field or class (Bukkit API, CraftBukkit or NMS) that does not exist in this version: the plugin was built for a different version of Minecraft/Paper.

Possible causes

  • The plugin version does not support the current Minecraft version (usually after a server update)
  • The plugin uses the versioned package org.bukkit.craftbukkit.vX_Y_RZ, which does not exist in Paper 1.20.5+ (no relocation)
  • Deprecated Bukkit API was removed/changed in the new Paper version

How to fixMedium risk

  1. Identify the plugin from the trace frames (the first frame from its jar/package after the exception line).
  2. Update the plugin to a version whose description lists support for your Minecraft version (Hangar/Modrinth/SpigotMC, the Versions/Changelog section).
  3. If there is no compatible version, temporarily roll the server back to a version the plugin supports (with a world backup) or replace the plugin with an alternative.
  4. Do not use /reload after replacing the jar — restart the server.

Translated from the Russian original; log lines are quoted verbatim.

Sources