I'm attempting to make a 1.20.1-47.4.0 forge server but when I change the user_jvm_args.txt it does nothing so i tried adding it to the run.bat which it picks up on the startup console but then gives me this

[21:56:01] [main/ERROR] [minecraft/Main]: Failed to start the minecraft server
joptsimple.UnrecognizedOptionException: X is not a recognized option
    at joptsimple.OptionException.unrecognizedOption(OptionException.java:108) ~[jopt-simple-5.0.4.jar%2393!/:?] {}
    at joptsimple.OptionParser.validateOptionCharacters(OptionParser.java:633) ~[jopt-simple-5.0.4.jar%2393!/:?] {}
    at joptsimple.OptionParser.handleShortOptionCluster(OptionParser.java:528) ~[jopt-simple-5.0.4.jar%2393!/:?] {}
    at joptsimple.OptionParser.handleShortOptionToken(OptionParser.java:523) ~[jopt-simple-5.0.4.jar%2393!/:?] {}
    at joptsimple.OptionParserState$2.handleArgument(OptionParserState.java:59) ~[jopt-simple-5.0.4.jar%2393!/:?] {}
    at joptsimple.OptionParser.parse(OptionParser.java:396) ~[jopt-simple-5.0.4.jar%2393!/:?] {}
    at net.minecraft.server.Main.main(Main.java:98) ~[server-1.20.1-20230612.114412-srg.jar%23101!/:?] {re:classloading}
    at jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:?] {}
    at jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:77) ~[?:?] {}
    at jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:?] {}
    at java.lang.reflect.Method.invoke(Method.java:568) ~[?:?] {}
    at net.minecraftforge.fml.loading.targets.CommonLaunchHandler.runTarget(CommonLaunchHandler.java:111) ~[fmlloader-1.20.1-47.4.0.jar%2369!/:?] {}
    at net.minecraftforge.fml.loading.targets.CommonLaunchHandler.serverService(CommonLaunchHandler.java:103) ~[fmlloader-1.20.1-47.4.0.jar%2369!/:?] {}
    at net.minecraftforge.fml.loading.targets.CommonServerLaunchHandler.lambda$makeService$0(CommonServerLaunchHandler.java:27) ~[fmlloader-1.20.1-47.4.0.jar%2369!/:?] {}
    at cpw.mods.modlauncher.LaunchServiceHandlerDecorator.launch(LaunchServiceHandlerDecorator.java:30) ~[modlauncher-10.0.9.jar%2355!/:?] {}
    at cpw.mods.modlauncher.LaunchServiceHandler.launch(LaunchServiceHandler.java:53) ~[modlauncher-10.0.9.jar%2355!/:?] {}
    at cpw.mods.modlauncher.LaunchServiceHandler.launch(LaunchServiceHandler.java:71) ~[modlauncher-10.0.9.jar%2355!/:?] {}
    at cpw.mods.modlauncher.Launcher.run(Launcher.java:108) ~[modlauncher-10.0.9.jar%2355!/:?] {}
    at cpw.mods.modlauncher.Launcher.main(Launcher.java:78) ~[modlauncher-10.0.9.jar%2355!/:?] {}
    at cpw.mods.modlauncher.BootstrapLaunchConsumer.accept(BootstrapLaunchConsumer.java:26) ~[modlauncher-10.0.9.jar%2355!/:?] {}
    at cpw.mods.modlauncher.BootstrapLaunchConsumer.accept(BootstrapLaunchConsumer.java:23) ~[modlauncher-10.0.9.jar%2355!/:?] {}
    at cpw.mods.bootstraplauncher.BootstrapLauncher.main(BootstrapLauncher.java:141) ~[bootstraplauncher-1.1.2.jar:?] {}

I have uninstalled and reinstalled all my versions of java and tried deleting and restarting everything several times to no avail. I have no more ideas and would appreciate any assistance.

joptsimple.UnrecognizedOptionException: X is not a recognized option

JVM-Arguments begin with a -

So use -Xmx6G instead of Xmx6G etc

I’ve tried both ways. Without the dash in the run.bat just makes it pop up in the console when launching. It does nothing in the jvm_args file and crashes it when it’s in the run.bat with dashes.

Add the lines of your run.bat here

On 9/12/2025 at 1:00 AM, TileEntity said:

Add the lines of your run.bat here

@echo off
REM Forge requires a configured set of both JVM and program arguments.
REM Add custom JVM arguments to the user_jvm_args.txt
REM Add custom program arguments {such as nogui} to this file in the next line before the %* or
REM  pass them to this script directly
java @user_jvm_args.txt @libraries/net/minecraftforge/forge/1.20.1-47.4.0/win_args.txt %*
pause
 

Make a test just with 

java -Xmx6G @libraries/net/minecraftforge/forge/1.20.1-47.4.0/win_args.txt %*
pause

If there is no change, directly set the java path in your script

1.20.1 requires Java 17

Download and install this version:

https://www.azul.com/downloads/?version=java-17-lts&os=windows&architecture=x86-64-bit&package=jdk#zulu

Then update the script to:

"C:\Program Files\Zulu\zulu-17\bin\javaw.exe" -Xmx6G @libraries/net/minecraftforge/forge/1.20.1-47.4.0/win_args.txt %*
pause

 

4 hours ago, TileEntity said:

Make a test just with 

java -Xmx6G @libraries/net/minecraftforge/forge/1.20.1-47.4.0/win_args.txt %*
pause

If there is no change, directly set the java path in your script

1.20.1 requires Java 17

Download and install this version:

https://www.azul.com/downloads/?version=java-17-lts&os=windows&architecture=x86-64-bit&package=jdk#zulu

Then update the script to:

"C:\Program Files\Zulu\zulu-17\bin\javaw.exe" -Xmx6G @libraries/net/minecraftforge/forge/1.20.1-47.4.0/win_args.txt %*
pause

 

It still launches without listening to the launch args. I have done a fresh install of windows, custom file paths and several versions of java. None of them change anything

Its working now and I'm not sure why. It still doesn't say it's using the launch args in the console but my memory utilization in the gui says otherwise so its all good for now. Thanks for the help and if i manage to narrow down what fixed it ill post it here in case someone has the same problem in the future.