MuntashirAkon/AppManager · error · IllegalArgumentException

Namespaces are not supported

Error message

Namespaces are not supported

What it means

BinaryXmlSerializer does not support XML namespaces: illegalNamespace() throws IllegalArgumentException whenever a non-null namespace is supplied to startTag, endTag, attribute, attributeInterned, attributeBytesHex, or attributeBytesBase64.

Solutions

  1. Pass null as the namespace argument to all serializer calls.
  2. Encode the namespace into the tag/attribute name (e.g. "ns:name") if namespacing semantics are needed.
  3. Switch to a namespaces-capable serializer (Xml.newSerializer with FEATURE_PROCESS_NAMESPACES) if namespaces are required.
  4. Refactor the document schema to avoid namespaces entirely.

Example fix

// before
serializer.startTag("http://schemas.android.com/apk/res/android", "manifest");
// after
serializer.startTag(null, "manifest");
Defensive patterns

Strategy: validation

Validate before calling

if (namespace != null) {
    throw new IllegalStateException("BinaryXmlSerializer does not support namespaces; pass null");
}

Try / catch

try {
    serializer.startTag(ns, name);
} catch (IllegalArgumentException e) {
    serializer.startTag(null, name); // retry namespace-free
}

Prevention

When it happens

Trigger: Calling serializer.startTag("http://example.com/ns", "tag"), serializer.attribute(ns, name, value), or any of the attribute* variants with a non-null namespace string.

Common situations: Porting code from XmlSerializer/Xml.newSerializer which accepts namespaces, or generating documents that originally used namespaced elements — Android's binary XML format intentionally drops namespace support.

Understand the failure class

Background: UnsupportedOperationException and "is not supported" errors: when a library deliberately refuses a call — this error's family across 30 libraries.

Related errors

AI-assisted analysis of MuntashirAkon/AppManager@0152f468fc (2026-09-12). Data as JSON: /api/errors/ab11d67ea192a79f. Report an issue: GitHub.

Appendix: source

Thrown at libcore/compat/src/main/java/io/github/muntashirakon/compat/xml/BinaryXmlSerializer.java:383

    public Object getProperty(String name) {
        // Properties are not supported
        throw new UnsupportedOperationException();
    }

    @Override
    public void setPrefix(String prefix, String namespace) {
        // Prefixes are not supported
        throw new UnsupportedOperationException();
    }

    @Override
    public String getPrefix(String namespace, boolean generatePrefix) {
        // Prefixes are not supported
        throw new UnsupportedOperationException();
    }

    private static IllegalArgumentException illegalNamespace() {
        throw new IllegalArgumentException("Namespaces are not supported");
    }
}

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