apache/maven · warning · RepositoryMetadataReadException

Cannot read metadata from '{}'

Error message

Cannot read metadata from '{}'

What it means

Eclipse Sisu converts plexus-style XML (components.xml/plexus.xml) into typed bean values via PlexusXmlBeanConverter. When a component field maps to String but the parser sits on a nested element (START_TAG) instead of text, Sisu mimics old Plexus behavior: it warns with the exact parser position (file, line, column), skips the subtree, and injects an empty string for that field.

Source

Thrown at compat/maven-compat/src/main/java/org/apache/maven/artifact/repository/metadata/DefaultRepositoryMetadataManager.java:278

            if (repoMetadata.getMetadata() != null) {
                setRepository = repoMetadata.getMetadata().merge(metadata);
            } else {
                repoMetadata.setMetadata(metadata);
                setRepository = true;
            }
        }
        return setRepository;
    }

    /*
     * TODO share with DefaultPluginMappingManager.
     */
    protected Metadata readMetadata(File mappingFile) throws RepositoryMetadataReadException {

        try (InputStream in = Files.newInputStream(mappingFile.toPath())) {
            return new Metadata(new MetadataStaxReader().read(in, false));
        } catch (FileNotFoundException e) {
            throw new RepositoryMetadataReadException("Cannot read metadata from '" + mappingFile + "'", e);
        } catch (IOException | XMLStreamException e) {
            throw new RepositoryMetadataReadException(
                    "Cannot read metadata from '" + mappingFile + "': " + e.getMessage(), e);
        }
    }

    /**
     * Ensures the last updated timestamp of the specified metadata does not refer to the future and fixes the local
     * metadata if necessary to allow proper merging/updating of metadata during deployment.
     */
    private void fixTimestamp(File metadataFile, Metadata metadata, Metadata reference) {
        boolean changed = false;

        if (metadata != null && reference != null) {
            Versioning versioning = metadata.getVersioning();
            Versioning versioningRef = reference.getVersioning();
            if (versioning != null && versioningRef != null) {
                String lastUpdated = versioning.getLastUpdated();

View on GitHub (pinned to e4093d4e12)

Solutions

1. Open the position named in the warning (it includes line and column) and flatten the value to plain text
2. Move structured data into a dedicated bean type the converter can build, instead of a String field
3. Prefer JSR-330/Sisu annotations over plexus XML to avoid the XML conversion heuristics entirely

Example fix

<!-- before: String field 'pattern' contains nested XML -->
<configuration>
  <pattern><value>.*</value></pattern>
</configuration>
<!-- after: plain text for the String property -->
<configuration>
  <pattern>.*</pattern>
</configuration>

# surface nested XML inside configuration values that map to String fields
xmllint --xpath '//configuration//*[*]' src/main/resources/META-INF/plexus/components.xml \
  && echo 'nested element found in a scalar configuration value'

When it happens

Trigger: A hand-written META-INF/plexus/components.xml or plexus.xml places child elements inside a configuration value that maps to a String bean property.

Common situations: Migrating legacy Plexus components to Sisu; copying old plexus examples into XML while the target field is a scalar; templates emitting nested defaults for simple values.

Related errors

• Unable to lookup org.eclipse.aether.RepositorySystem
• Error in component graph of plugin ${plugin.getId()}: ${e.ge
• Unable to load the mojo '${mojoDescriptor.getGoal()}' (or on
• %nThere can only be one user supplied ConfigurationProcessor
• No binding to construct an instance for key {}. Existing bi

AI-assisted analysis of apache/maven@e4093d4e12 (2026-08-21). Data as JSON: /api/errors/50225e9e6af15939. Report an issue: GitHub.