1.12 can't test mod

[fieryzombie31]

Running the mods worked in 1.11 on same computer, same environment. When I try to launch my mod I get this error:

java.lang.ClassNotFoundException: net.minecraftforge.fml.common.launcher.FMLTweaker
at java.net.URLClassLoader.findClass(URLClassLoader.java:381) ~[?:1.8.0_131]
at java.lang.ClassLoader.loadClass(ClassLoader.java:424) ~[?:1.8.0_131]
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:335) ~[?:1.8.0_131]
at java.lang.ClassLoader.loadClass(ClassLoader.java:357) ~[?:1.8.0_131]
at net.minecraft.launchwrapper.LaunchClassLoader.findClass(LaunchClassLoader.java:106) ~[launchwrapper-1.12.jar:?]
at java.lang.ClassLoader.loadClass(ClassLoader.java:424) ~[?:1.8.0_131]
at java.lang.ClassLoader.loadClass(ClassLoader.java:357) ~[?:1.8.0_131]
at java.lang.Class.forName0(Native Method) ~[?:1.8.0_131]
at java.lang.Class.forName(Class.java:348) ~[?:1.8.0_131]
at net.minecraft.launchwrapper.Launch.launch(Launch.java:98) [launchwrapper-1.12.jar:?]
at net.minecraft.launchwrapper.Launch.main(Launch.java:28) [launchwrapper-1.12.jar:?]
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:1.8.0_131]
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[?:1.8.0_131]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:1.8.0_131]
at java.lang.reflect.Method.invoke(Method.java:498) ~[?:1.8.0_131]
at net.minecraftforge.gradle.GradleStartCommon.launch(GradleStartCommon.java:97) [start/:?]
at GradleStart.main(GradleStart.java:26) [start/:?]

 

[jeffryfisher]

Did you mess with the  gradle file? You can get errors like this if you mess up the reobfuscation (or if you "export" from Eclipse instead of running gradlew build).

[fieryzombie31]

I used the FORGE_CLIENT run thing