apache/maven · warning

The last updated timestamp in {} refers to the future (now =

Error message

The last updated timestamp in {} refers to the future (now = {}, lastUpdated = {}). Please verify that the clocks of all deploying machines are reasonably synchronized.

What it means

Warning from DefaultRepositoryMetadataManager.fixTimestamp while resolving/installing metadata: the lastUpdated timestamp in the local maven-metadata.xml is in the future relative to the freshly read reference (now). Maven assumes clock skew between deploying machines, warns, and repairs the local copy by overwriting lastUpdated with 'now' (changed=true, triggering a rewrite of the file).

Source

Thrown at compat/maven-compat/src/main/java/org/apache/maven/artifact/repository/metadata/DefaultRepositoryMetadataManager.java:300

        }
    }

    /**
     * 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();
                String now = versioningRef.getLastUpdated();
                if (lastUpdated != null && now != null && now.compareTo(lastUpdated) < 0) {
                    getLogger()
                            .warn("The last updated timestamp in " + metadataFile + " refers to the future (now = "
                                    + now
                                    + ", lastUpdated = " + lastUpdated + "). Please verify that the clocks of all"
                                    + " deploying machines are reasonably synchronized.");
                    versioning.setLastUpdated(now);
                    changed = true;
                }
            }
        }

        if (changed) {
            getLogger().debug("Repairing metadata in " + metadataFile);

            try (OutputStream out = Files.newOutputStream(metadataFile.toPath())) {
                new MetadataStaxWriter().write(out, metadata.getDelegate());
            } catch (IOException | XMLStreamException e) {
                String msg = "Could not write fixed metadata to " + metadataFile + ": " + e.getMessage();
                if (getLogger().isDebugEnabled()) {
                    getLogger().warn(msg, e);

View on GitHub (pinned to e4093d4e12)

Solutions

1. Enable NTP/chrony on all build and deploy machines so clocks stay synchronized.
2. Verify date -u on the machine that produced the metadata matches reality.
3. For the local file, the repair happens automatically (lastUpdated is reset to now); to also fix the remote, redeploy the artifact or rebuild repository metadata.
4. Check for timezone bugs in custom plugins that write Metadata objects with hand-formatted timestamps.

Example fix

# before: skew
local agent: date -u -> 2026-08-21 10:00:00 (5 min fast)
# after
sudo chronyc makestep   # or: sudo ntpd -gq / w32tm /resync
<!-- maven-metadata.xml repaired automatically: -->
<lastUpdated>20260821095500</lastUpdated>

# compare local clock with a trusted source before deploying
ntpdate -q pool.ntp.org | awk '/offset/ {print $NF}'  # or: chronyc tracking

When it happens

Trigger: resolve/resolveAlways merges remote and local metadata: versioning.lastUpdated of the local file > lastUpdated of the reference just fetched. Causes: a machine with a fast clock previously deployed or wrote metadata; timezone-formatted timestamps (yyyyMMddHHmmss compared lexicographically, so format/UTC-vs-local mismatches compare as future); manually bumped timestamps.

Common situations: CI agents without NTP synchronization deploying snapshots; VMs resuming from suspend with skewed clocks; regions with wrong timezone writing local-time timestamps where UTC was expected; developer laptops with dead CMOS batteries.

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/d56d342d32d4098c. Report an issue: GitHub.