I am creating a server for myself and a bunch of friends to play on, but i cannot get it to work. I have tried fresh installs of forge and different versions of 1.10.2 and nothing has worked . It gives me this when I try to start it. 

 

A problem occurred running the Server launcher.java.lang.reflect.InvocationTarge
tException
        at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Nativ
e Method)
        at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(Unknow
n Source)
        at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(Un
known Source)
        at java.base/java.lang.reflect.Method.invoke(Unknown Source)
        at net.minecraftforge.fml.relauncher.ServerLaunchWrapper.run(ServerLaunc
hWrapper.java:62)
        at net.minecraftforge.fml.relauncher.ServerLaunchWrapper.main(ServerLaun
chWrapper.java:31)
Caused by: java.lang.ClassCastException: java.base/jdk.internal.loader.ClassLoad
ers$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
Press any key to continue . . .

 

 

Thanks for any help. 

 

Edit: I tried different versions of forge entirely(1.12 and 1.11) and those also game me the same startup error. 

Edited February 16, 20187 yr by AreUThreateningMe

Fixed it, reinstalled Java completely. 

Forge doesn't support Java 9, you need to use Java 8.