apache/maven · warning

The metadata {} {}{}

Error message

The metadata {} {}{}

What it means

Warning emitted by LoggingRepositoryListener.metadataInvalid when artifact metadata (maven-metadata.xml) downloaded from a repository fails post-fetch validation (MetadataInvalidException). The suffix 'is inaccessible' (instead of 'is invalid') is used when the underlying exception is FileNotFoundException, e.g. the local file vanished. With -X debug enabled the full exception (with stack trace) is attached; without it only the exception message. Resolution continues; the metadata is treated as absent.

Source

Thrown at impl/maven-core/src/main/java/org/apache/maven/internal/aether/LoggingRepositoryListener.java:84

        Object metadata;
        if (event.getMetadata().getFile() != null) {
            metadata = event.getMetadata().getFile();
        } else {
            metadata = event.getMetadata();
        }

        String errorType = " is invalid";
        if (exception instanceof FileNotFoundException) {
            errorType = " is inaccessible";
        }

        String msg = "";
        if (exception != null) {
            msg = ": " + exception.getMessage();
        }

        if (logger.isDebugEnabled()) {
            logger.warn("The metadata {} {}{}", metadata, errorType, msg, exception);
        } else {
            logger.warn("The metadata {} {}{}", metadata, errorType, msg);
        }
    }

    @Override
    public void artifactDescriptorInvalid(RepositoryEvent event) {
        // The exception stack trace is not really interesting here
        logger.warn(
                "The POM for {} is invalid, transitive dependencies (if any) will not be available: {}",
                event.getArtifact(),
                event.getException().getMessage());
    }

    @Override
    public void artifactDescriptorMissing(RepositoryEvent event) {
        logger.warn("The POM for {} is missing, no dependency information available", event.getArtifact());
    }

View on GitHub (pinned to e4093d4e12)

Solutions

1. Run with -X to get the underlying exception and the failing file/URI.
2. Delete the local cached copy (find ~/.m2/repository -name 'maven-metadata*.xml' in the artifact's path) and re-resolve.
3. Fetch the metadata URL with curl to inspect what the server actually returns; fix the server/proxy if it is not valid XML.
4. If server-side, ask the repository admin to repair or redeploy the affected metadata (rebuild metadata index in Nexus/Artifactory).

Example fix

# before: stale/corrupt local metadata keeps failing
# after: purge and re-resolve
rm ~/.m2/repository/com/example/artifact/maven-metadata-*.xml
mvn -U dependency:resolve

# verify local metadata parses before building
for f in $(find ~/.m2/repository -name 'maven-metadata*.xml'); do
  python3 -c "import xml.dom.minidom,sys; xml.dom.minidom.parse('$f')" || echo "CORRUPT: $f"
done

When it happens

Trigger: Repository listener fires after metadata check/download: the served maven-metadata.xml is malformed (truncated, HTML error page stored as XML, bad checksum content) or the local metadata file was deleted between discovery and parse. Non-debug builds get exactly this one-line warn with errorType ' is invalid' or ' is inaccessible'.

Common situations: Proxies returning a login HTML page where metadata XML is expected; partially uploaded metadata on the server; local repository corruption from interrupted downloads or disk issues; concurrent builds deleting each other's temp files.

Related errors

• Cannot read metadata from '{}': {}
• {} could not be retrieved from repository: {} due to an erro
• Error installing metadata: {}
• Error while deploying metadata: {}
• Cannot add two different pieces of metadata for: " + getKey(

AI-assisted analysis of apache/maven@e4093d4e12 (2026-08-21). Data as JSON: /api/errors/ad309ef59286f698. Report an issue: GitHub.