Can't start the FTB Revelations server

[Spameo_HD]

So, I am trying to host an FTB Revelation server, version 3.4.0. The problem is that every time I try to start the server, it gives me the following error:

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:567)
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

I tried using the .bat file, the .jar file and even the console, all of wich failed. Am I doing something wrong?

 

[Woahdang_Jr]

It is possible you don't have Java installed properly. I am having the same problem.

 

[mellodoot]

forgot I was following this thread a couple months back- my solution was simple, so simple it hurt when I figured it out.

double-check what version of Java you're running. Modern modpacks/vanilla versions can run on modern Java versions just fine, but for whatever reason FTB Rev has to be running on Java 1.8. Having this version installed and using it to run your server should run with no issues.

hope this helps!!