apache/maven · warning

Invalid artifact version {}: {}

Error message

Invalid artifact version {}: {}

What it means

Warning from DefaultArtifactResolver.resolve when a resolved SNAPSHOT artifact's version matches Artifact.VERSION_FILE_PATTERN (timestamped snapshot like 1.0-20260821.123456-7): group(3) should be the build number, but Integer.parseInt on it throws NumberFormatException. Maven logs 'Invalid artifact version' and simply skips attaching SnapshotArtifactRepositoryMetadata (build number/timestamp metadata) for that artifact; resolution itself is not rolled back.

Source

Thrown at compat/maven-compat/src/main/java/org/apache/maven/artifact/resolver/DefaultArtifactResolver.java:215

                } else {
                    throw new ArtifactResolutionException(e.getMessage(), artifact, remoteRepositories, e);
                }
            }

            artifact.selectVersion(result.getArtifact().getVersion());
            artifact.setFile(result.getArtifact().getFile());
            artifact.setResolved(true);

            if (artifact.isSnapshot()) {
                Matcher matcher = Artifact.VERSION_FILE_PATTERN.matcher(artifact.getVersion());
                if (matcher.matches()) {
                    Snapshot snapshot = new Snapshot();
                    snapshot.setTimestamp(matcher.group(2));
                    try {
                        snapshot.setBuildNumber(Integer.parseInt(matcher.group(3)));
                        artifact.addMetadata(new SnapshotArtifactRepositoryMetadata(artifact, snapshot));
                    } catch (NumberFormatException e) {
                        logger.warn("Invalid artifact version " + artifact.getVersion() + ": " + e.getMessage());
                    }
                }
            }
        }
    }

    @Override
    public ArtifactResolutionResult resolveTransitively(
            Set<Artifact> artifacts,
            Artifact originatingArtifact,
            ArtifactRepository localRepository,
            List<ArtifactRepository> remoteRepositories,
            ArtifactMetadataSource source,
            ArtifactFilter filter)
            throws ArtifactResolutionException, ArtifactNotFoundException {
        return resolveTransitively(
                artifacts,
                originatingArtifact,

View on GitHub (pinned to e4093d4e12)

Solutions

1. Locate the declaration: mvn dependency:tree -Dverbose and grep for the malformed timestamped version; correct it to a proper -SNAPSHOT or a well-formed timestamped version (-N with numeric N).
2. If the bad artifact sits in the local repository, delete that artifact's directory and re-resolve from a clean source.
3. Check mirrors/repository rewriting rules (Nexus/Artifactory version policies) that could alter snapshot filenames.
4. Regenerate any scripts that construct version strings to enforce the <base>-<timestamp>-<buildNumber> format.

Example fix

<!-- before -->
<version>1.2-20260821.101010-abc</version>
<!-- after: rely on snapshot metadata -->
<version>1.2-SNAPSHOT</version>

private static final Pattern TS = Pattern.compile("^(.*)-(\\d{8}\\.\\d{6})-(\\d+)$");
boolean wellFormedSnapshotVersion(String v) { return TS.matcher(v).matches(); }

When it happens

Trigger: A snapshot artifact version string whose suffix after the timestamp is non-numeric, e.g. 1.0-20260821.123456-x or 1.0-20260821.123456- (empty), reaches resolve(). This typically means a hand-crafted version in a dependency declaration, a mirror rewriting version strings, or a repository serving malformed snapshot filenames that got installed into the local repo.

Common situations: Manually pinned timestamped snapshot versions in pom.xml with typos; dependency:go-offline or scripts fabricating version strings; custom repository managers that mangle snapshot filenames; migrating from formats like -SNAPSHOT-1 to pure timestamped forms incorrectly.

Related errors

• Error retrieving previous build number for artifact '" + art
• Could not parse current Maven version: {}
• Cannot read metadata from '{}': {}
• {} could not be retrieved from repository: {} due to an erro
• Error installing metadata: {}

AI-assisted analysis of apache/maven@e4093d4e12 (2026-08-21). Data as JSON: /api/errors/3dadf3565c9c48f2. Report an issue: GitHub.