apache/maven · error · IllegalArgumentException

reader or inputStream must be non null

Error message

reader or inputStream must be non null

What it means

DefaultToolchainsXmlFactory.read accepts only a Reader or an InputStream; path and url on the request are not consulted. If both reader and inputStream are null it throws IllegalArgumentException before parsing a PersistedToolchains document.

Source

Thrown at impl/maven-impl/src/main/java/org/apache/maven/impl/DefaultToolchainsXmlFactory.java:55

import org.apache.maven.api.toolchain.InputSource;
import org.apache.maven.api.toolchain.PersistedToolchains;
import org.apache.maven.toolchain.v4.MavenToolchainsStaxReader;
import org.apache.maven.toolchain.v4.MavenToolchainsStaxWriter;

import static java.util.Objects.requireNonNull;
import static org.apache.maven.impl.StaxLocation.getLocation;
import static org.apache.maven.impl.StaxLocation.getMessage;

@Named
@Singleton
public class DefaultToolchainsXmlFactory implements ToolchainsXmlFactory {
    @Override
    public PersistedToolchains read(@Nonnull XmlReaderRequest request) throws XmlReaderException {
        Objects.requireNonNull(request, "request");
        Reader reader = request.getReader();
        InputStream inputStream = request.getInputStream();
        if (reader == null && inputStream == null) {
            throw new IllegalArgumentException("reader or inputStream must be non null");
        }
        try {
            InputSource source = null;
            if (request.getModelId() != null || request.getLocation() != null) {
                source = InputSource.of(request.getLocation());
            }
            MavenToolchainsStaxReader xml = request.getTransformer() != null
                    ? new MavenToolchainsStaxReader(request.getTransformer()::transform)
                    : new MavenToolchainsStaxReader();
            xml.setAddDefaultEntities(request.isAddDefaultEntities());
            if (reader != null) {
                return xml.read(reader, request.isStrict(), source);
            } else {
                return xml.read(inputStream, request.isStrict(), source);
            }
        } catch (Exception e) {
            throw new XmlReaderException("Unable to read toolchains: " + getMessage(e), getLocation(e), e);
        }

View on GitHub (pinned to e4093d4e12)

Solutions

1. Open the file and pass .inputStream(Files.newInputStream(path)) or .reader(Files.newBufferedReader(path))
2. Check getReader()/getInputStream() for null before calling read

Example fix

// before
PersistedToolchains t = toolchainsXmlFactory.read(XmlReaderRequest.builder()
    .path(toolchainsPath) // ignored: wants reader or inputStream
    .build()); // throws

// after\ntry (InputStream is = Files.newInputStream(toolchainsPath)) {\n    PersistedToolchains t = toolchainsXmlFactory.read(XmlReaderRequest.builder()\n        .inputStream(is)\n        .build());\n}

XmlReaderRequest req = XmlReaderRequest.builder().build();
if (req.getReader() == null && req.getInputStream() == null) {
    try (InputStream is = Files.newInputStream(toolchainsPath)) {
        toolchainsXmlFactory.read(XmlReaderRequest.builder()
            .inputStream(is)
            .build());
    }
} else {
    toolchainsXmlFactory.read(req);
}

When it happens

Trigger: Building a XmlReaderRequest for toolchains with only .path(...) or .url(...) set (ignored by this factory), or with no source at all.

Common situations: Reusing request-builder code from factories that do support path/url; assuming the XML factory APIs are symmetric across model, plugin, settings and toolchains.

Understand the failure class

Background: "missing required argument" and "the following required arguments were not provided": what required-argument errors mean and how to fix them — this error's family across 20 libraries.

Related errors

• path, url, reader or inputStream must be non null
• reader or inputStream must be non null
• writer or outputStream must be non null
• Cannot read toolchains file at " + userToolchainsFile.getAbs
• writer, outputStream or path must be non null

AI-assisted analysis of apache/maven@e4093d4e12 (2026-08-21). Data as JSON: /api/errors/783a8844c60ba825. Report an issue: GitHub.