C:\Users\Administrator\Desktop\server>java -Xms20G -jar forge.jar

A problem occurred running the Server launcher.java.lang.reflect.InvocationTargetException

    at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:109)

    at java.base/java.lang.reflect.Method.invoke(Method.java:580)

    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)

    at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:103)

    ... 3 more