How to Check If a Mod Requires Kotlin for Forge

Reading the Mod's Dependencies

When a mod fails to load or crashes on startup, the culprit is often a missing Kotlin for Forge library. Open your mods folder and look at the mod's own page or its mods.toml/neoforge.mods.toml metadata. Mods that depend on Kotlin for Forge will list it as a required dependency, often named "Kotlin for Forge" or "kotlinforforge". If you see that entry, the mod cannot run without the library present.

Confirming It Is Loaded

Launch the game and open the Mods list from the main menu. Kotlin for Forge should appear as its own entry alongside your other mods. If it is missing, the dependent mod will usually show a red error or be absent from the list entirely. Check the latest log file in your logs folder for lines mentioning Kotlin or a missing dependency; these tell you exactly which mod is asking for it.

What To Do Next

If the library is present but a mod still complains, make sure both files sit directly in the mods folder and are not nested inside a subfolder or archive. Remove duplicate copies of the library if you have more than one, since conflicting versions can prevent loading. Once the dependency resolves, the dependent mod should appear normally in the Mods list.