What causes "snapshot source has less than two snapshots" in kopia/kopia?

Run another backup to create a second snapshot

snapshot source has less than two snapshots

Error message

snapshot source has less than two snapshots

What it means

GetTwoLatestSnapshotsForASource requires at least two snapshots for a source to return the last and second-last manifests. If fewer than two exist, it returns this error since no pair can be returned.

Solutions

Run another backup to create a second snapshot
Guard the call by counting snapshots via snapshot.ListSnapshots first
Treat the error as 'nothing to compare' and skip the diff
Manually specify two known snapshot IDs using a diff API that takes explicit IDs

Example fix

// before
prev, last, err := diff.GetTwoLatestSnapshotsForASource(ctx, rep, source)
// after
snaps, _ := snapshot.ListSnapshots(ctx, rep, source)
if len(snaps) < 2 {
    return nil // only %d snapshot(s) exist
}
prev, last, err := diff.GetTwoLatestSnapshotsForASource(ctx, rep, source)

Defensive patterns

Strategy: validation

Validate before calling

snaps, err := snapshot.ListSnapshots(ctx, rep, source)
if err != nil || len(snaps) < 2 {
    return nil // fewer than two snapshots
}

Try / catch

prev, last, err := diff.GetTwoLatestSnapshotsForASource(ctx, rep, source)
if err != nil && strings.Contains(err.Error(), "less than two") {
    return nil // nothing to diff yet
}

Prevention

Schedule at least two backups before enabling diff-based reporting
Check snapshot count before comparing
Skip new sources gracefully in batch jobs

When it happens

Trigger: Calling GetTwoLatestSnapshotsForASource for a source with 0 or 1 snapshots.

Common situations: First run of a diff/reporting tool on a newly configured source; a source that has only had one backup ever taken.

Understand the failure class

Background: EmptyResultError / "no results found": when an API or scraper succeeds but returns zero rows — this error's family across 9 libraries.

Related errors

AI-assisted analysis of kopia/kopia@82495e54b5 (2026-09-07). Data as JSON: /api/errors/bf12b75a59f603c2. Report an issue: GitHub.

Appendix: source

Thrown at internal/diff/diff.go:459

			return snapshotList[i-1], nil
		}
	}

	return nil, errors.New("couldn't find immediately preceding snapshot")
}

// GetTwoLatestSnapshotsForASource fetches two latest snapshot manifests for a given source if they exist.
func GetTwoLatestSnapshotsForASource(ctx context.Context, rep repo.Repository, source snapshot.SourceInfo) (secondLast, last *snapshot.Manifest, err error) {
	snapshots, err := snapshot.ListSnapshots(ctx, rep, source)
	if err != nil {
		return nil, nil, errors.Wrap(err, "failed to list all snapshots")
	}

	const minimumReqSnapshots = 2

	sizeSnapshots := len(snapshots)
	if sizeSnapshots < minimumReqSnapshots {
		return nil, nil, errors.New("snapshot source has less than two snapshots")
	}

	sort.Slice(snapshots, func(i, j int) bool {
		return snapshots[i].StartTime.Before(snapshots[j].StartTime)
	})

	return snapshots[sizeSnapshots-2], snapshots[sizeSnapshots-1], nil
}

View on GitHub (pinned to 82495e54b5)