iBotPeaches/Apktool · error · AndrolibException

Repeated alias: pkgId=0x%02x, aliasId=%s

Error message

Repeated alias: pkgId=0x%02x, aliasId=%s

What it means

AndrolibException thrown by ResPackage.addAlias(aliasId, finalId) when the alias id is already mapped in mAliases. Aliases redirect one resource id to another (common in obfuscated/collapsed resource tables); each alias id may be registered only once. Note the sibling resolveAlias throws 'alias: pkgId=..., aliasId=...' (error in the same SOURCE block) when looking up an unregistered alias.

Source

Thrown at brut.apktool/apktool-lib/src/main/java/brut/androlib/res/table/ResPackage.java:346

        return mOverlayables.values();
    }

    public boolean isAlias(ResId resId) {
        return mAliases.containsKey(resId);
    }

    public ResId resolveAlias(ResId aliasId) throws UndefinedResObjectException {
        ResId resId = mAliases.get(aliasId);
        if (resId == null) {
            throw new UndefinedResObjectException(
                String.format("alias: pkgId=0x%02x, aliasId=%s", getId(), aliasId));
        }
        return resId;
    }

    public void addAlias(ResId aliasId, ResId finalId) throws AndrolibException {
        if (mAliases.containsKey(aliasId)) {
            throw new AndrolibException(
                String.format("Repeated alias: pkgId=0x%02x, aliasId=%s", getId(), aliasId));
        }

        mAliases.put(aliasId, finalId);
    }

    public int getAliasCount() {
        return mAliases.size();
    }

    public Map<ResId, ResId> getAliases() {
        return mAliases;
    }

    @Override
    public String toString() {
        return String.format("ResPackage{id=0x%02x, name=%s}", getId(), getName());
    }

View on GitHub (pinned to 79b63384d7)

Solutions

  1. Before addAlias, check getAliases().containsKey(aliasId) and skip or update instead of re-adding.
  2. For parsed files, a genuine duplicate alias indicates corruption — validate with aapt2 and re-obtain the APK.
  3. Keep alias generation deterministic (sort/dedupe) when emitting arsc yourself.

Example fix

// before
pkg.addAlias(aliasId, finalId); // throws if already mapped

// after
if (!pkg.getAliases().containsKey(aliasId)) {
    pkg.addAlias(aliasId, finalId);
}
Defensive patterns

Strategy: validation

Validate before calling

if (!pkg.getAliases().containsKey(aliasId)) {
    pkg.addAlias(aliasId, finalId);
}

Try / catch

try {
    pkg.addAlias(aliasId, finalId);
} catch (AndrolibException ex) {
    // duplicate alias mapping -> corrupt or replayed table; report
}

Prevention

When it happens

Trigger: An arsc with two alias definitions for the same source id; programmatic table construction registering the same alias twice; alias chains where an id is both alias and target mapped repeatedly.

Common situations: Resource-obfuscation output (collapsed ids) with duplicated mapping entries; merged or patched arsc files; rebuild tools replaying alias registration.

Related errors

AI-assisted analysis of iBotPeaches/Apktool@79b63384d7 (2026-08-14). Data as JSON: /api/errors/4862bffc06052e87. Report an issue: GitHub.