apache/maven · error · UnsupportedOperationException

Cannot change the version information for an attached artifa

Error message

Cannot change the version information for an attached artifact. It is derived from the main artifact.

What it means

AttachedArtifact delegates available-version metadata to its parent: getAvailableVersions() returns the main artifact's list, while setAvailableVersions throws UnsupportedOperationException because that metadata is owned by the main artifact.

Source

Thrown at impl/maven-core/src/main/java/org/apache/maven/project/artifact/AttachedArtifact.java:86

    public AttachedArtifact(Artifact parent, String type, ArtifactHandler artifactHandler) {
        this(parent, type, null, artifactHandler);
    }

    @Override
    public void setArtifactId(String artifactId) {
        throw new UnsupportedOperationException(
                "Cannot change the artifactId for an attached artifact." + " It is derived from the main artifact.");
    }

    @Override
    public List<ArtifactVersion> getAvailableVersions() {
        return parent.getAvailableVersions();
    }

    @Override
    public void setAvailableVersions(List<ArtifactVersion> availableVersions) {
        throw new UnsupportedOperationException("Cannot change the version information for an attached artifact."
                + " It is derived from the main artifact.");
    }

    @Override
    public String getBaseVersion() {
        return parent.getBaseVersion();
    }

    @Override
    public void setBaseVersion(String baseVersion) {
        throw new UnsupportedOperationException("Cannot change the version information for an attached artifact."
                + " It is derived from the main artifact.");
    }

    @Override
    public String getDownloadUrl() {
        return parent.getDownloadUrl();
    }

View on GitHub (pinned to e4093d4e12)

Solutions

Set available versions on the main artifact (project.getArtifact().setAvailableVersions(...)) and let attachments inherit it
Use a standalone DefaultArtifact for artifacts that need independent metadata
Skip attached artifacts when stamping metadata

Example fix

// before
for (Artifact a : project.getAttachedArtifacts()) {
    a.setAvailableVersions(versions);
}

// after
project.getArtifact().setAvailableVersions(versions);

Defensive patterns

Strategy: type-guard

Type guard

static boolean isAttachedArtifact(Artifact a) {
    return a instanceof org.apache.maven.project.artifact.AttachedArtifact;
}

Try / catch

if (isAttachedArtifact(artifact)) {
    project.getArtifact().setAvailableVersions(versions); // metadata is owned by the main artifact
} else {
    artifact.setAvailableVersions(versions);
}

Prevention

Apply version-metadata updates to the main artifact once, not per attached artifact
Skip attached artifacts in generic normalization passes

When it happens

Trigger: Calling setAvailableVersions(list) on an AttachedArtifact, e.g. resolution or version-metadata code that stamps available versions onto every artifact of a project.

Common situations: Version-range tooling or resolvers iterating project.getAttachedArtifacts() and normalizing metadata on each entry; code ported from DefaultArtifact-based flows where the setter worked.

Related errors

AI-assisted analysis of apache/maven@e4093d4e12 (2026-08-21). Data as JSON: /api/errors/16f0ae410097590e. Report an issue: GitHub.