apache/maven · error · XmlReaderException

Unable to read model:

Error message

Unable to read model: 

What it means

DefaultModelXmlFactory.doRead funnels every failure of the actual parse/write pipeline into XmlReaderException('Unable to read model: <detail>'). The wrapped causes include XML well-formedness errors, strict-mode schema validation failures, IO problems opening the path/URL stream, and encoding issues. The exception carries the parsed StaxLocation (line/column) so the exact position in the POM can be reported.

Source

Thrown at impl/maven-impl/src/main/java/org/apache/maven/impl/DefaultModelXmlFactory.java:149

            MavenStaxReader xml = request.getTransformer() != null
                    ? new MavenStaxReader(request.getTransformer()::transform)
                    : new MavenStaxReader();
            xml.setAddDefaultEntities(request.isAddDefaultEntities());
            if (inputStream != null) {
                return xml.read(inputStream, request.isStrict(), source);
            } else if (reader != null) {
                return xml.read(reader, request.isStrict(), source);
            } else if (path != null) {
                try (InputStream is = Files.newInputStream(path)) {
                    return xml.read(is, request.isStrict(), source);
                }
            } else {
                try (InputStream is = url.openStream()) {
                    return xml.read(is, request.isStrict(), source);
                }
            }
        } catch (Exception e) {
            throw new XmlReaderException("Unable to read model: " + getMessage(e), getLocation(e), e);
        }
    }

    @Override
    public void write(XmlWriterRequest<Model> request) throws XmlWriterException {
        requireNonNull(request, "request");
        Model content = requireNonNull(request.getContent(), "content");
        Path path = request.getPath();
        OutputStream outputStream = request.getOutputStream();
        Writer writer = request.getWriter();

        if (writer == null && outputStream == null && path == null) {
            throw new IllegalArgumentException("writer, outputStream or path must be non null");
        }

        try {
            MavenStaxWriter xmlWriter = new MavenStaxWriter();
            xmlWriter.setAddLocationInformation(false);

View on GitHub (pinned to e4093d4e12)

Solutions

1. Check e.getLocation() for line/column and validate the file as XML first (xmllint or IDE XML inspection)
2. For strict-mode failures, fix the offending element per the schema for the declared modelVersion, or set strict(false) if tolerant reading is acceptable
3. For URL/path sources, confirm the resource is reachable/intact (re-download, check HTTP status) and that the encoding matches the XML declaration
4. Report the cause chain (e.getCause()) since the top-level message only prefixes the detail

Example fix

// before
Model model = factory.read(XmlReaderRequest.builder().path(pom).build());

// after
try {
    Model model = factory.read(XmlReaderRequest.builder().path(pom).build());
} catch (XmlReaderException e) {
    System.err.printf('Invalid POM %s at line %d col %d: %s%n',
            pom, e.getLocation().getLineNumber(), e.getLocation().getColumnNumber(), e.getMessage());
    throw e;
}

// quick well-formedness check before the real read
var f = javax.xml.XMLInputFactory.newInstance();
try (var is = Files.newInputStream(pom)) {
    var r = f.createXMLStreamReader(is);
    while (r.hasNext()) r.next();
}

try {
    Model model = factory.read(XmlReaderRequest.builder().path(pom).build());
} catch (XmlReaderException e) {
    var loc = e.getLocation(); // line/column in the POM
    // report loc + e.getCause(); if strict validation, fix the element or retry with strict(false)
}

When it happens

Trigger: Reading a pom.xml that is not well-formed XML (unclosed tag, stray &), fails strict validation against the schema (unknown element for the declared modelVersion), cannot be opened (missing file, HTTP 404 for a URL), or has a declared encoding that does not match the bytes.

Common situations: Hand-edited POMs with XML typos or unescaped ampersands in URLs; comments or elements not valid for the modelVersion; interrupted downloads leaving truncated POMs in the local repo; CI fetching POMs over flaky HTTP; wrong file encoding after editing on Windows.

Related errors

• path, url, reader or inputStream must be non null
• Cannot read metadata from '{}': {}
• Repository identifier missing
• URL missing for repository " + id
• Repository identifier missing

AI-assisted analysis of apache/maven@e4093d4e12 (2026-08-21). Data as JSON: /api/errors/5bc32b125352d6d4. Report an issue: GitHub.