I've tried a number of times to build and run the example mod and keep encountering the same error. I've tried switching JVMs, redownloading the Forge MDK, and restarting my laptop. I followed the steps to start modding available here, starting at 'From Zero to Modding' and, after step #5, jumping to step #2 in 'Building and Testing Your Mod'.

 

Any help is greatly appreciated.
Apologies in advance if it's something stupid on my part.

 

Quote

[00:41:22] [pool-2-thread-1/DEBUG] [ne.mi.fm.ja.FMLJavaModLanguageProvider/SCAN]: Found @Mod class com.example.examplemod.ExampleMod with id examplemod
[00:41:23] [Render thread/INFO] [minecraft/Minecraft]: Setting user: Dev
[00:41:24] [Render thread/DEBUG] [ne.mi.co.tr.CoreModBaseTransformer/COREMOD]: Transforming net/minecraft/block/FlowingFluidBlock
[00:41:24] [Render thread/DEBUG] [ne.mi.co.tr.CoreModBaseTransformer/COREMOD]: Transforming net/minecraft/block/StairsBlock
[00:41:25] [Render thread/DEBUG] [ne.mi.co.tr.CoreModBaseTransformer/COREMOD]: Transforming net/minecraft/block/FlowerPotBlock
[00:41:30] [Render thread/DEBUG] [ne.mi.co.tr.CoreModBaseTransformer/COREMOD]: Transforming net/minecraft/item/BucketItem
[00:41:30] [Render thread/DEBUG] [ne.mi.co.tr.CoreModBaseTransformer/COREMOD]: Transforming net/minecraft/item/FishBucketItem
[00:41:31] [Render thread/DEBUG] [ne.mi.co.tr.CoreModBaseTransformer/COREMOD]: Transforming net/minecraft/potion/EffectInstance
[00:41:35] [Render thread/INFO] [minecraft/Minecraft]: Backend library: LWJGL version 3.2.1 build 12
[00:41:37] [Render thread/INFO] [STDOUT/]: [net.minecraft.util.registry.Bootstrap:printToSYSOUT:109]: ---- Minecraft Crash Report ----
// This doesn't make any sense!

Time: 27/04/20 12:41 AM
Description: Initializing game

java.lang.NoSuchMethodError: java.nio.ByteBuffer.rewind()Ljava/nio/ByteBuffer;
    at net.minecraft.client.MainWindow.loadIcon(MainWindow.java:188) ~[forge-1.15.2-31.1.0_mapped_snapshot_20190719-1.14.3-recomp.jar:?] {re:classloading,pl:runtimedistcleaner:A}
    at net.minecraft.client.MainWindow.setWindowIcon(MainWindow.java:152) ~[forge-1.15.2-31.1.0_mapped_snapshot_20190719-1.14.3-recomp.jar:?] {re:classloading,pl:runtimedistcleaner:A}
    at net.minecraft.client.Minecraft.<init>(Minecraft.java:380) ~[forge-1.15.2-31.1.0_mapped_snapshot_20190719-1.14.3-recomp.jar:?] {re:classloading,pl:accesstransformer:B,pl:runtimedistcleaner:A}
    at net.minecraft.client.main.Main.main(Main.java:141) ~[forge-1.15.2-31.1.0_mapped_snapshot_20190719-1.14.3-recomp.jar:?] {re:classloading,pl:runtimedistcleaner:A}
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:1.8.0_252] {}
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[?:1.8.0_252] {}
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:1.8.0_252] {}
    at java.lang.reflect.Method.invoke(Method.java:498) ~[?:1.8.0_252] {}
    at net.minecraftforge.userdev.FMLUserdevClientLaunchProvider.lambda$launchService$0(FMLUserdevClientLaunchProvider.java:55) ~[forge-1.15.2-31.1.0_mapped_snapshot_20190719-1.14.3-recomp.jar:?] {}
    at cpw.mods.modlauncher.LaunchServiceHandlerDecorator.launch(LaunchServiceHandlerDecorator.java:37) [modlauncher-5.0.0-milestone.4.jar:?] {}
    at cpw.mods.modlauncher.LaunchServiceHandler.launch(LaunchServiceHandler.java:54) [modlauncher-5.0.0-milestone.4.jar:?] {}
    at cpw.mods.modlauncher.LaunchServiceHandler.launch(LaunchServiceHandler.java:72) [modlauncher-5.0.0-milestone.4.jar:?] {}
    at cpw.mods.modlauncher.Launcher.run(Launcher.java:81) [modlauncher-5.0.0-milestone.4.jar:?] {}
    at cpw.mods.modlauncher.Launcher.main(Launcher.java:65) [modlauncher-5.0.0-milestone.4.jar:?] {}
    at net.minecraftforge.userdev.LaunchTesting.main(LaunchTesting.java:102) [forge-1.15.2-31.1.0_mapped_snapshot_20190719-1.14.3-recomp.jar:?] {}

A detailed walkthrough of the error, its code path and all known details is as follows:
---------------------------------------------------------------------------------------

-- Head --
Thread: Render thread
Stacktrace:
    at net.minecraft.client.MainWindow.loadIcon(MainWindow.java:188)
    at net.minecraft.client.MainWindow.setWindowIcon(MainWindow.java:152)
    at net.minecraft.client.Minecraft.<init>(Minecraft.java:380)

-- Initialization --
Details:
Stacktrace:
    at net.minecraft.client.main.Main.main(Main.java:141)
    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:498)
    at net.minecraftforge.userdev.FMLUserdevClientLaunchProvider.lambda$launchService$0(FMLUserdevClientLaunchProvider.java:55)
    at cpw.mods.modlauncher.LaunchServiceHandlerDecorator.launch(LaunchServiceHandlerDecorator.java:37)
    at cpw.mods.modlauncher.LaunchServiceHandler.launch(LaunchServiceHandler.java:54)
    at cpw.mods.modlauncher.LaunchServiceHandler.launch(LaunchServiceHandler.java:72)
    at cpw.mods.modlauncher.Launcher.run(Launcher.java:81)
    at cpw.mods.modlauncher.Launcher.main(Launcher.java:65)
    at net.minecraftforge.userdev.LaunchTesting.main(LaunchTesting.java:102)

-- System Details --
Details:
    Minecraft Version: 1.15.2
    Minecraft Version ID: 1.15.2
    Operating System: Mac OS X (x86_64) version 10.15.4
    Java Version: 1.8.0_252, AdoptOpenJDK
    Java VM Version: OpenJDK 64-Bit Server VM (mixed mode), AdoptOpenJDK
    Memory: 533802864 bytes (509 MB) / 1007157248 bytes (960 MB) up to 1908932608 bytes (1820 MB)
    CPUs: 8
    JVM Flags: 1 total; -Xss1M
    Launched Version: MOD_DEV
    Backend library: LWJGL version 3.2.1 build 12
    Backend API: NVIDIA GeForce GT 650M OpenGL Engine GL version 2.1 NVIDIA-14.0.32 355.11.11.10.10.143, NVIDIA Corporation
    GL Caps:
    Using VBOs: Yes
    Is Modded: Definitely; Client brand changed to 'forge'
    Type: Client (map_client.txt)
    CPU: <unknown>

 

Process finished with exit code 255

 

Cheers! It worked flawlessly this morning. Thanks for tracking that down.