FML Gradle - FAILURE: Build failed with an exception

Question

Recently I have been setting up a Minecraft Forge workspace on eclipse. I have created minecraft mods with forge in the past ( MC1.6.4 and such) although a lot has changed since then. I am trying to mod using Forge1.15.2-31.1.0 mdk AND JDK 1.8.0_241

I created a RunClient.bat file in my workspace folder to compile and build my project

it fully builds and compiles to 98% and then crashes. This is my crash report:

    ---- Minecraft Crash Report ----
// I bet Cylons wouldn’t have this problem.

Time: 13/04/20 2:16 PM
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.(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_241] {}
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[?:1.8.0_241] {}
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:1.8.0_241] {}
at java.lang.reflect.Method.invoke(Method.java:498) ~[?:1.8.0_241] {}
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.(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: Windows 10 (amd64) version 10.0
Java Version: 1.8.0_241, Oracle Corporation
Java VM Version: Java HotSpot™ 64-Bit Server VM (mixed mode), Oracle Corporation
Memory: 928980168 bytes (885 MB) / 1747976192 bytes (1667 MB) up to 3817865216 bytes (3641 MB)
CPUs: 4
JVM Flags: 2 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx4096m
Launched Version: MOD_DEV
Backend library: LWJGL version 3.2.2 build 10
Backend API: GeForce GTX 1060 6GB/PCIe/SSE2 GL version 4.6.0 NVIDIA 445.75, NVIDIA Corporation
GL Caps:
Using VBOs: Yes
Is Modded: Definitely; Client brand changed to ‘forge’
Type: Client (map_client.txt)
CPU:

--UPDATED 2020-04-16-- JDK 13 crash report:

---- Minecraft Crash Report ----
// Why did you do that?

Time: 2020-04-12, 9:11 p.m.
Description: Initializing game

java.lang.ExceptionInInitializerError: null
    at net.minecraftforge.fml.ModLoader.<init>(ModLoader.java:121) ~[forge-1.15.2-31.1.0_mapped_snapshot_20190719-1.14.3-recomp.jar:?] {re:classloading}
    at net.minecraftforge.fml.ModLoader.get(ModLoader.java:146) ~[forge-1.15.2-31.1.0_mapped_snapshot_20190719-1.14.3-recomp.jar:?] {re:classloading}
    at net.minecraftforge.fml.client.ClientModLoader.lambda$begin$2(ClientModLoader.java:97) ~[forge-1.15.2-31.1.0_mapped_snapshot_20190719-1.14.3-recomp.jar:?] {re:classloading,pl:runtimedistcleaner:A}
    at net.minecraftforge.fml.client.ClientModLoader.lambda$createRunnableWithCatch$5(ClientModLoader.java:113) ~[forge-1.15.2-31.1.0_mapped_snapshot_20190719-1.14.3-recomp.jar:?] {re:classloading,pl:runtimedistcleaner:A}
    at net.minecraftforge.fml.client.ClientModLoader.begin(ClientModLoader.java:97) ~[forge-1.15.2-31.1.0_mapped_snapshot_20190719-1.14.3-recomp.jar:?] {re:classloading,pl:runtimedistcleaner:A}
    at net.minecraft.client.Minecraft.<init>(Minecraft.java:393) ~[forge-1.15.2-31.1.0_mapped_snapshot_20190719-1.14.3-recomp.jar:?] {re:classloading,pl:accesstransformer:B,pl:runtimedistcleaner:A}
    at net.minecraft.client.main.Main.main(Main.java:141) ~[forge-1.15.2-31.1.0_mapped_snapshot_20190719-1.14.3-recomp.jar:?] {re:classloading,pl:runtimedistcleaner:A}
    at jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:?] {}
    at jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[?:?] {}
    at jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:?] {}
    at java.lang.reflect.Method.invoke(Method.java:567) ~[?:?] {}
    at net.minecraftforge.userdev.FMLUserdevClientLaunchProvider.lambda$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:?] {}
Caused by: java.lang.IllegalStateException: Failed to resolve consumer event type: net.minecraftforge.fml.network.simple.SimpleChannel$$Lambda$2199/0x000000080140ec40@2c4e63b3
    at net.minecraftforge.eventbus.EventBus.addListener(EventBus.java:194) ~[eventbus-2.0.0-milestone.1-service.jar:?] {}
    at net.minecraftforge.eventbus.EventBus.addListener(EventBus.java:161) ~[eventbus-2.0.0-milestone.1-service.jar:?] {}
    at net.minecraftforge.eventbus.EventBus.addListener(EventBus.java:156) ~[eventbus-2.0.0-milestone.1-service.jar:?] {}
    at net.minecraftforge.eventbus.EventBus.addListener(EventBus.java:151) ~[eventbus-2.0.0-milestone.1-service.jar:?] {}
    at net.minecraftforge.fml.network.NetworkInstance.addListener(NetworkInstance.java:65) ~[?:?] {re:classloading}
    at net.minecraftforge.fml.network.simple.SimpleChannel.<init>(SimpleChannel.java:56) ~[?:?] {re:classloading}
    at net.minecraftforge.fml.network.simple.SimpleChannel.<init>(SimpleChannel.java:49) ~[?:?] {re:classloading}
    at net.minecraftforge.fml.network.NetworkRegistry$ChannelBuilder.simpleChannel(NetworkRegistry.java:409) ~[?:?] {re:classloading}
    at net.minecraftforge.fml.network.NetworkInitialization.getHandshakeChannel(NetworkInitialization.java:38) ~[?:?] {re:classloading}
    at net.minecraftforge.fml.network.FMLNetworkConstants.<clinit>(FMLNetworkConstants.java:48) ~[?:?] {re:classloading}
    ... 18 more


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

-- Head --
Thread: Render thread
Stacktrace:
    at net.minecraftforge.fml.ModLoader.<init>(ModLoader.java:121)
    at net.minecraftforge.fml.ModLoader.get(ModLoader.java:146)
    at net.minecraftforge.fml.client.ClientModLoader.lambda$begin$2(ClientModLoader.java:97)
    at net.minecraftforge.fml.client.ClientModLoader.lambda$createRunnableWithCatch$5(ClientModLoader.java:113)
    at net.minecraftforge.fml.client.ClientModLoader.begin(ClientModLoader.java:97)
    at net.minecraft.client.Minecraft.<init>(Minecraft.java:393)

-- Initialization --
Details:
Stacktrace:
    at net.minecraft.client.main.Main.main(Main.java:141)
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.base/java.lang.reflect.Method.invoke(Method.java:567)
    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: Windows 10 (amd64) version 10.0
    Java Version: 13.0.2, Oracle Corporation
    Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode, sharing), Oracle Corporation
    Memory: 1419176960 bytes (1353 MB) / 2276458496 bytes (2171 MB) up to 6392119296 bytes (6096 MB)
    CPUs: 4
    JVM Flags: 2 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx6096m
    Launched Version: MOD_DEV
    Backend library: LWJGL version 3.2.2 build 10
    Backend API: GeForce GTX 1060 6GB/PCIe/SSE2 GL version 4.6.0 NVIDIA 445.75, NVIDIA Corporation
    GL Caps: Using framebuffer using OpenGL 3.0
    Using VBOs: Yes
    Is Modded: Definitely; Client brand changed to 'forge'
    Type: Client (map_client.txt)
    CPU: 4x Intel(R) Core(TM) i5-6600K CPU @ 3.50GHz

--UPDATED 2020-04-17-- Workspace rebuilt (compiled and ran against Java 8):

---- Minecraft Crash Report ----
// Daisy, daisy...

Time: 17/04/20 6:50 PM
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_241] {}
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[?:1.8.0_241] {}
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:1.8.0_241] {}
    at java.lang.reflect.Method.invoke(Method.java:498) ~[?:1.8.0_241] {}
    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: Windows 10 (amd64) version 10.0
    Java Version: 1.8.0_241, Oracle Corporation
    Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
    Memory: 620772560 bytes (592 MB) / 1550319616 bytes (1478 MB) up to 3817865216 bytes (3641 MB)
    CPUs: 4
    JVM Flags: 2 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx4096m
    Launched Version: MOD_DEV
    Backend library: LWJGL version 3.2.2 build 10
    Backend API: GeForce GTX 1060 6GB/PCIe/SSE2 GL version 4.6.0 NVIDIA 445.75, NVIDIA Corporation
    GL Caps: 
    Using VBOs: Yes
    Is Modded: Definitely; Client brand changed to 'forge'
    Type: Client (map_client.txt)
    CPU: <unknown>

Answer 1

In Java 8, ByteBuffer.rewind() returns a Buffer , but in Java 13, it returns a ByteBuffer . Your first crash report indicates that you compiled against Java 13 but ran against Java 8, which doesn't work. Your second crash report is because Forge still doesn't support running on Java 13 yet. To fix your problem, clear all of your build caches and recompile with the Java 8 compiler. Once you do that, you'll be able to run with Java 8.