Having trouble with converting from Windows to Linux dedicated server..

[Dranemra]

So, silly me, I figured that - being Java - it didn't matter what platform I would run my server on... so I have Mint Cinnamon installed to run my server.

First of all I can't run my original batch file as a command line:

java -d64 -Xincgc -Xmx8g -Dfml.readTimeout=420 -XX:+AggressiveOpts -XX:+UseConcMarkSweepGC -XX:+UseParNewGC -XX:+CMSIncrementalPacing -XX:ParallelGCThreads=2 -jar forge-1.12.2-14.23.5.2847-universal.jar

Java won't recognize any of the environment handlers I put in outside of the max memory limit... when I truncate it down, it still doesn't run, from what I can tell, it's not even trying to load Forge at all. I get.

java -Xmx6G -jar forge-1.12.2-14.23.5.2847-universal.jar 
A problem occurred running the Server launcher.java.lang.reflect.InvocationTargetException
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.base/java.lang.reflect.Method.invoke(Method.java:566)
	at net.minecraftforge.fml.relauncher.ServerLaunchWrapper.run(ServerLaunchWrapper.java:70)
	at net.minecraftforge.fml.relauncher.ServerLaunchWrapper.main(ServerLaunchWrapper.java:34)
Caused by: java.lang.ClassCastException: class jdk.internal.loader.ClassLoaders$AppClassLoader cannot be cast to class java.net.URLClassLoader (jdk.internal.loader.ClassLoaders$AppClassLoader and java.net.URLClassLoader are in module java.base of loader 'bootstrap')
	at net.minecraft.launchwrapper.Launch.<init>(Launch.java:34)
	at net.minecraft.launchwrapper.Launch.main(Launch.java:28)
	... 6 more

From what I can tell, I have installed Java, it skipped all the way up to

openjdk version "11.0.4" 2019-07-16
OpenJDK Runtime Environment (build 11.0.4+11-post-Ubuntu-1ubuntu218.04.3)
OpenJDK 64-Bit Server VM (build 11.0.4+11-post-Ubuntu-1ubuntu218.04.3, mixed mode)

When I do version check... So I'm somewhat at a loss as to where this is crapping out. I hope I've provided enough information, I've been running Forge servers off of windows for over a year now, and figured I'd know how to handle most simple issues, but I'm at a loss as to where to start.

Edited October 1, 2019 by Dranemra

[DaemonUmbra]

Forge for 1.12.2 requires you to use Java 8 exactly, nothing later.

[Dranemra]

Okay, so this is going to sound super noobish, but how does one downgrade java from 11 to 8 in linux.. So far instructions I've found online want to me install the 8 jdk directly from Oracle who - for some reason won't let me even create an account them as my access is 'blocked'

 

Edit: I found it in the end.. Mint had a bunch of open java 11 installed in their software suite.. it took awhile to find it but it's working.

Thank you for the tip.

Edited October 1, 2019 by Dranemra
solved