Hello! I am encountering an issue when trying to run 1.17.1 mdk client (gradle). Im using intellij and have downloaded Forge 1.17.1 37.0.104 mdk and followed instructions and imported it into intellij. I have changed all of the necessary fields for classes and mod id's etc but no matter what I do I encounter this error below. Ive tried multiple tutorials on starting and every time I get this issue. I am running Java 16 with the correct version gradle. I have also tried many different versions of forge 1.17.1. Forge 1.16 and below work perfectly fine. If anyone can help me out It would be much appreciated 

 

Exception in thread "main" java.lang.RuntimeException: java.lang.StringIndexOutOfBoundsException: begin 0, end -1, length 3
    at MC-BOOTSTRAP/[email protected]/cpw.mods.modlauncher.LaunchServiceHandlerDecorator.launch(LaunchServiceHandlerDecorator.java:39)
    at MC-BOOTSTRAP/[email protected]/cpw.mods.modlauncher.LaunchServiceHandler.launch(LaunchServiceHandler.java:53)
    at MC-BOOTSTRAP/[email protected]/cpw.mods.modlauncher.LaunchServiceHandler.launch(LaunchServiceHandler.java:71)
    at MC-BOOTSTRAP/[email protected]/cpw.mods.modlauncher.Launcher.run(Launcher.java:106)
    at MC-BOOTSTRAP/[email protected]/cpw.mods.modlauncher.Launcher.main(Launcher.java:77)
    at MC-BOOTSTRAP/[email protected]/cpw.mods.modlauncher.BootstrapLaunchConsumer.accept(BootstrapLaunchConsumer.java:26)
    at MC-BOOTSTRAP/[email protected]/cpw.mods.modlauncher.BootstrapLaunchConsumer.accept(BootstrapLaunchConsumer.java:23)
    at [email protected]/cpw.mods.bootstraplauncher.BootstrapLauncher.main(BootstrapLauncher.java:90)
Caused by: java.lang.StringIndexOutOfBoundsException: begin 0, end -1, length 3
    at java.base/java.lang.String.checkBoundsBeginEnd(String.java:3751)
    at java.base/java.lang.String.substring(String.java:1907)
    at [email protected]/cpw.mods.cl.ModuleClassLoader.loadClass(ModuleClassLoader.java:128)
    at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:519)
    at java.base/java.lang.Class.getDeclaredMethods0(Native Method)
    at java.base/java.lang.Class.privateGetDeclaredMethods(Class.java:3334)
    at java.base/java.lang.Class.getMethodsRecursive(Class.java:3475)
    at java.base/java.lang.Class.getMethod0(Class.java:3461)
    at java.base/java.lang.Class.getMethod(Class.java:2193)
    at MC-BOOTSTRAP/[email protected]/net.minecraftforge.fml.loading.targets.ForgeClientUserdevLaunchHandler.lambda$launchService$0(ForgeClientUserdevLaunchHandler.java:38)
    at MC-BOOTSTRAP/[email protected]/cpw.mods.modlauncher.LaunchServiceHandlerDecorator.launch(LaunchServiceHandlerDecorator.java:37)
    ... 7 more

I also sometimes get this error? 
 

Exception in thread "main" java.lang.IllegalArgumentException: : Invalid module name: '' is not a Java identifier
	at java.base/jdk.internal.module.Checks.requireModuleName(Checks.java:59)
	at java.base/java.lang.module.ModuleDescriptor$Builder.<init>(ModuleDescriptor.java:1523)
	at java.base/java.lang.module.ModuleDescriptor.newAutomaticModule(ModuleDescriptor.java:2405)
	at [email protected]/cpw.mods.jarhandling.impl.SimpleJarMetadata.descriptor(SimpleJarMetadata.java:13)
	at [email protected]/cpw.mods.jarhandling.impl.Jar.computeDescriptor(Jar.java:47)
	at [email protected]/cpw.mods.cl.JarModuleFinder$JarModuleReference.<init>(JarModuleFinder.java:50)
	at [email protected]/cpw.mods.cl.JarModuleFinder.lambda$new$0(JarModuleFinder.java:28)
	at java.base/java.util.stream.ReferencePipeline$3$1.accept(ReferencePipeline.java:197)
	at java.base/java.util.Spliterators$ArraySpliterator.forEachRemaining(Spliterators.java:948)
	at java.base/java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:484)
	at java.base/java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:474)
	at java.base/java.util.stream.ReduceOps$ReduceOp.evaluateSequential(ReduceOps.java:913)
	at java.base/java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234)
	at java.base/java.util.stream.ReferencePipeline.collect(ReferencePipeline.java:682)
	at [email protected]/cpw.mods.cl.JarModuleFinder.<init>(JarModuleFinder.java:29)
	at [email protected]/cpw.mods.cl.JarModuleFinder.of(JarModuleFinder.java:43)
	at [email protected]/cpw.mods.bootstraplauncher.BootstrapLauncher.main(BootstrapLauncher.java:81)

Process finished with exit code 1

If I missed any information yall need let me know and Ill hand it over ❤️

Thanks!!

try editing the runClient configuration, setting the module (there is a dropdown) and running it again...

On 11/5/2021 at 3:46 PM, MFMods said:

try editing the runClient configuration, setting the module (there is a dropdown) and running it again...

Unfortunately after a few attempts this did not help

Can you show us your build.gradle?