Anuken/Mindustry · error · ModLoadException

A mod with the name '{baseName}' is already imported.

Error message

A mod with the name '{baseName}' is already imported.

What it means

When importing a mod, if another mod with the same baseName already exists and cannot be overwritten (e.g. it has a Steam ID), loadMod throws ModLoadException. Non-Steam duplicates are silently overwritten; Steam ones must be removed via unsubscribe.

Source

Thrown at core/src/mindustry/mod/Mods.java:1133

                        Fi cacheDir = new Fi(Core.files.getCachePath()).child("mods");
                        Fi modCacheDir = cacheDir.child(other.file.nameWithoutExtension());
                        modCacheDir.deleteDirectory();
                    }

                    //close zip file
                    if(other.root instanceof ZipFi){
                        other.root.delete();
                    }
                    //delete the old mod directory
                    if(other.file.isDirectory()){
                        other.file.deleteDirectory();
                    }else{
                        other.file.delete();
                    }
                    //unload
                    mods.remove(other);
                }else{
                    throw new ModLoadException("A mod with the name '" + baseName + "' is already imported.");
                }
            }

            ClassLoader loader = null;
            Mod mainMod;
            Fi mainFile = zip;

            if(android){
                mainFile = mainFile.child("classes.dex");
            }else{
                String[] path = (mainClass.replace('.', '/') + ".class").split("/");
                for(String str : path){
                    if(!str.isEmpty()){
                        mainFile = mainFile.child(str);
                    }
                }
            }

View on GitHub (pinned to f695ad7e60)

Solutions

1. Unsubscribe the existing Steam mod first, then import.
2. Rename your mod's 'name' field to a unique baseName.
3. Remove the duplicate from the mods directory.

Example fix

// before: meta.json name "example" collides with subscribed Steam mod
// after: change "name": "example" to "name": "example-dev"

// Check for an existing same-name mod before importing.
String baseName = meta.name.toLowerCase(Locale.ROOT).replace(" ", "-");
LoadedMod existing = mods.getMods().find(m -> m.name.equals(baseName));
if(existing != null && existing.hasSteamID()) {
    throw new ModLoadException("Conflict with Steam mod '" + baseName + "'; unsubscribe first.");
}

boolean nameIsFree(Mods mods, String name){
    String base = name.toLowerCase(Locale.ROOT).replace(" ", "-");
    return mods.getMods().noneMatch(m -> m.name.equals(base));
}

try {
    mods.importMod(file);
} catch(ModLoadException e) {
    if(e.getMessage().contains("already imported")) { /* unsubscribe Steam dup or rename */ }
    else throw e;
}

When it happens

Trigger: Importing a local mod whose normalized name matches an already-imported Steam mod (hasSteamID() true).

Common situations: Re-importing a mod also installed from Steam; two mods sharing the same name field; development copy colliding with a subscribed Workshop item.

Related errors

• Invalid file: No mod.json found.
• This mod/plugin has loaded Mindustry dependencies from its o
• Two content objects defined with the same name: '{content.na
• Attribute definitions must be objects, e.g. {heat: 10}
• Unknown status effect: '

AI-assisted analysis of Anuken/Mindustry@f695ad7e60 (2026-08-14). Data as JSON: /api/errors/f54c6f9702a73134. Report an issue: GitHub.