Crash when launching

[Yafi]

Unable to launch

java.lang.reflect.InvocationTargetException

       at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)

       at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)

       at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)

       at java.lang.reflect.Method.invoke(Method.java:497)

       at net.minecraft.launchwrapper.Launch.launch(Launch.java:135)

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

Caused by: java.lang.NoClassDefFoundError: net/minecraft/world/World

       at net.minecraft.client.main.Main.main(SourceFile:38)

       ... 6 more

Caused by: java.lang.ClassNotFoundException: net.minecraft.world.World

       at net.minecraft.launchwrapper.LaunchClassLoader.findClass(LaunchClassLoader.java:191)

       at java.lang.ClassLoader.loadClass(ClassLoader.java:424)

       at java.lang.ClassLoader.loadClass(ClassLoader.java:357)

       ... 7 more

Caused by: java.lang.ClassFormatError: Duplicate interface name in class file net/minecraft/world/World

       at java.lang.ClassLoader.defineClass1(Native Method)

       at java.lang.ClassLoader.defineClass(ClassLoader.java:760)

       at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)

       at net.minecraft.launchwrapper.LaunchClassLoader.findClass(LaunchClassLoader.java:182)

       ... 9 more

 

what should i do to fix this?

Edited January 25, 2020 by Yafi