Anuken/Mindustry · error · IllegalArgumentException

Unknown unit stance name:

Error message

Unknown unit stance name: 

What it means

Thrown by the UnitStance parser when data is a string but content.unitStance(name) returns null, i.e. no stance with that name is registered.

Source

Thrown at core/src/mindustry/mod/ContentParser.java:173

        put(UnitCommand.class, (type, data) -> {
            if(data.isString()){
               var cmd = content.unitCommand(data.asString());
               if(cmd != null){
                   return cmd;
               }else{
                   throw new IllegalArgumentException("Unknown unit command name: " + data.asString());
               }
            }else{
                throw new IllegalArgumentException("Unit commands must be strings.");
            }
        });
        put(UnitStance.class, (type, data) -> {
            if(data.isString()){
                var cmd = content.unitStance(data.asString());
                if(cmd != null){
                    return cmd;
                }else{
                    throw new IllegalArgumentException("Unknown unit stance name: " + data.asString());
                }
            }else{
                throw new IllegalArgumentException("Unit stances must be strings.");
            }
        });
        put(BulletType.class, (type, data) -> {
            if(data.isString()){
                return field(Bullets.class, data);
            }else if(data.isArray()){
                return new MultiBulletType(parser.readValue(BulletType[].class, data));
            }
            Class<?> alternate = resolve(Strings.capitalize(data.getString("type", "basic")) + "BulletType", Object.class, false);
            Class<?> bc = alternate == Object.class ? resolve(data.getString("type", ""), BasicBulletType.class) : alternate;
            data.remove("type");
            BulletType result = (BulletType)make(bc);
            result.minfo.mod = currentMod;
            readFields(result, data);
            return result;

View on GitHub (pinned to f695ad7e60)

Solutions

1. Verify the stance name against registered unit stances.
2. Confirm the game version supports that stance.
3. Check mod load order if provided by another mod.

Example fix

// before
"stance": "pursue"
// after
"stance": "pursueEnemy"

// Verify a unit stance name is registered.
boolean stanceExists(String name) {
    return Vars.content.unitStance(name) != null;
}

When it happens

Trigger: A mod JSON references a unit stance by a string name absent from the stance registry.

Common situations: Typo, stance not available in the current game version, or referencing content from an unloaded mod.

Related errors

• Unit stances must be strings.
• Attribute definitions must be objects, e.g. {heat: 10}
• Unknown status effect: '
• Unknown unit command name:
• Unit commands must be strings.

AI-assisted analysis of Anuken/Mindustry@f695ad7e60 (2026-08-14). Data as JSON: /api/errors/5a27323eec70c182. Report an issue: GitHub.