I've created forge servers in the past, but it has been a few years. I downloaded the installer and extracted the file, and then ran the server and changed the EULA to true. I run the vanilla server again and generate the world and basic files, then I switch to the forge server file. But I am getting the below code when I try to run the forge server file, whether I run the vanilla world first or not. 

 

When I researched it previously, it sounded like it was a problem with December 2017, so now that we are in 2018 I am trying it again and getting the below code. 

 

I am running on a brand new Mac with java fully updated (I checked, and even uninstalled and reinstalled for good measure). Not sure what other information you may need, please let me know.

 

Launch Code:

 

#!/bin/bash
cd "$(dirname "$0")"
exec java -Xms1G -Xmx1G -jar forge_server.jar nogui

 

Terminal Code:

 

Last login: Mon Jan  1 11:48:32 on ttys000

xxx/Desktop/untitled\ folder/start.command ; exit;

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:564)

at net.minecraftforge.fml.relauncher.ServerLaunchWrapper.run(ServerLaunchWrapper.java:62)

at net.minecraftforge.fml.relauncher.ServerLaunchWrapper.main(ServerLaunchWrapper.java:31)

Caused by: java.lang.ClassCastException: java.base/jdk.internal.loader.ClassLoaders$AppClassLoader cannot be cast to java.base/java.net.URLClassLoader

at net.minecraft.launchwrapper.Launch.<init>(Launch.java:34)

at net.minecraft.launchwrapper.Launch.main(Launch.java:28)

... 6 more

logout

Saving session...

...copying shared history...

...saving history...truncating history files...

...completed.

 

[Process completed]

On 1/1/2018 at 2:05 PM, diesieben07 said:

Use Java 8, not 9.

Thank you for the response. I am running Java 8. My husband has tried on his PC with similar luck and is also running Java 8. 

Your log is running Java 9. And the only cause of this issue is you running java 9. So be sure.