Startup Issue with Minecraft - Minecraft FTB Ultimate doesn't start

Technical Support
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1

System Information

Field Value
Operating System Linux - Debian GNU/Linux 12 on x86_64
Product AMP ‘Phobos’ v2.6.4.0 (Mainline)
Virtualization Docker
Application Minecraft
Module MinecraftModule
Running in Container Yes
Current State Stopped

Problem Description

Issue

when starting the server, the console spits out this error:
Error: A JNI error has occurred, please check your installation and try again
Exception in thread “main” java.lang.UnsupportedClassVersionError: net/minecraft/bundler/Main has been compiled by a more recent version of the Java Runtime (class file version 65.0), this version of the Java Runtime only recognizes class file versions up to 52.0
i’m already using java 8 so i don’t know what other version i should use

Reproduction Steps

  • change to ftb ultimate
  • change java version to temurin 8
  • update instance (ftb installed successfully)
  • start server
2

Check that you have the right server type and modloader version selected after the FTB pack is installed