org.spongepowered.asm.launch.MixinInitialisationError

[hookclaw]

Minecraft Version

26.1 (LTS)

Mod Loader

Forge

Describe the Issue

I am testing this using "IntelliJ IDEA 2026.1.3".
Although I have been developing with NeoForged for about three months, this is my first time working with "balm," so I am not entirely sure how it works.
I downloaded "balm-mod 26.1 (2026/06/26)" and tried running it as-is (using runClient).
The NeoForge Client and Fabric Client launched without any issues.
However, I wasn't sure how to launch it for Forge, so I tried [:forge:runClient] and [:forge:runTestClient].
This resulted in a runtime error.
Compilation succeeded, but I suspect the following JSON files are missing:

yourmod.mixins.json (Found)
yourmod-api.mixins.json (Not found)
yourmod-forge.mixins.json (Found yourmod.forge.mixins.json)

I am not sure what the correct configuration should be, but I wanted to report this for now.

Logs

[error message]

Caused by: org.spongepowered.asm.launch.MixinInitialisationError: Error initialising mixin config yourmod.mixins.json,yourmod-api.mixins.json,yourmod-forge.mixins.json

Caused by: java.lang.IllegalArgumentException: The specified resource 'yourmod.mixins.json,yourmod-api.mixins.json,yourmod-forge.mixins.json' was invalid or could not be read

Execution failed for task ':forge:runClient'.

Process 'command 'C:\Program Files\Java\jdk-25.0.2\bin\java.exe'' finished with non-zero exit value 1

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BUILD FAILED in 4s
13 actionable tasks: 1 executed, 12 up-to-date

latest.log

[BlayTheNinth]

It's a typo in the template. Update your run args in forge/build.gradle to fix: 3b08fee

Additionally, you have to fix the balm-forge dependency to use the non-slim jar, as it crashes with a Jar-in-Jar error otherwise (e668cb5). You may also have to update to the latest version of Balm (8f7b4ad).

[hookclaw]

It's resolved. Thank you.