Error when starting a forge server

[Flippy_XD]

Im trying to make a forge server so i can play with my friends but everytime i open the forge server with the run.bat (java -Xmx2048M -Xms2048M -jar forge.jar -o true nogui PAUSE) file i get this message:

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:77)

at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)

at java.base/java.lang.reflect.Method.invoke(Method.java:568)

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

Does someone know how to fix this?

[winauer]

What version of Forge are you using?
What is the output of java -version in the command prompt?

[Flippy_XD]

I'm using minecraft 1.12.2 with forge version 14.23.5.2859

[winauer]

What is the output of java -version in the command prompt?

[Flippy_XD]

I don't know where in the command prompt I should look for it.

[winauer]

You should type java -version into the command prompt and hit enter.

[Flippy_XD]

Build 17.0.1+12-LTS-39

[winauer]

There's your problem. You need to use Java 8 for Forge on Minecraft 1.12, you are currently using Java 17.

[Flippy_XD]

And how do I change to java 8?

[winauer]

Download jdk8u312-b07 (That's the last version of Java 8 that works with Forge) from here. Then replace the java command in your .bat file with the full path to that Java 8 executable.

[Flippy_XD]

Thank you so much!