I am able to compile and build a jar with Forge 1.12.2-14.23.0.2528 but the game crashes during start up with

 

java.lang.NoSuchFieldError: ROCK
    at com.palancarmedia.kazCraft.blocks.SimpleStoneBlock.<init>(SimpleStoneBlock.java:11)
    at com.palancarmedia.kazCraft.blocks.ModBlocks.<clinit>(ModBlocks.java:5)
    at com.palancarmedia.kazCraft.handlers.BlockHandler.registerBlocks(BlockHandler.java:75)
    at net.minecraftforge.fml.common.eventhandler.ASMEventHandler_41_BlockHandler_registerBlocks_Register.invoke(.dynamic)
    at net.minecraftforge.fml.common.eventhandler.ASMEventHandler.invoke(ASMEventHandler.java:90)
    at net.minecraftforge.fml.common.eventhandler.EventBus$1.invoke(EventBus.java:143)
    at net.minecraftforge.fml.common.eventhandler.EventBus.post(EventBus.java:179)
    at net.minecraftforge.registries.GameData.fireRegistryEvents(GameData.java:734)
    at net.minecraftforge.fml.common.Loader.preinitializeMods(Loader.java:603)
    at net.minecraftforge.fml.client.FMLClientHandler.beginMinecraftLoading(FMLClientHandler.java:270)
    at net.minecraft.client.Minecraft.func_71384_a(Minecraft.java:466)
    at net.minecraft.client.Minecraft.func_99999_d(Minecraft.java:377)
    at net.minecraft.client.main.Main.main(SourceFile:123)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
    at java.lang.reflect.Method.invoke(Unknown Source)
    at net.minecraft.launchwrapper.Launch.launch(Launch.java:135)
    at net.minecraft.launchwrapper.Launch.main(Launch.java:28)

fml-client-3.log

SimpleStoneBlock.java

Not sure, but I've encountered same error if I take the mod file (built with gradlew runClient/Server) and put it into my .minecraft/mod folder.  What I have to do it use gradlew build and move that file when I am ready to move into my minecraft/mod folder (out of development environment). Maybe your issue or not...

1 hour ago, diesieben07 said:

The build task obfuscates your mod, this is need to run in actual Minecraft. You must use this to produce your mod jar.

Thanks, makes sense once you know about it.

using gradlew build fixed the issue.  Thanks.