Post-sync backup promoted an unexpected target version; oper

Error message

Post-sync backup promoted an unexpected target version; operation will be retried: splitId={}, source={}, target={}, checkpointId={}

What it means

After promoting the staged file to the backup target, the enumerator validates that the promoted content matches the captured source version (length+mtime, or a SHA-256 content fingerprint when available). This WARN fires when the target exists but does not match the expected version, so the operation returns FAILED_RETRYABLE rather than declaring success over wrong data. It guards against overwriting or mistaking another file's content as the backup.

Source

Thrown at seatunnel-connectors-v2/connector-file/connector-file-base/src/main/java/org/apache/seatunnel/connectors/seatunnel/file/source/split/ContinuousMultipleTableFileSourceSplitEnumerator.java:945

        if (!isSinkTargetCommitted(ctx, op, checkpointId, stagingPath)) {
            return handleRetryableStagedOperation(
                    ctx, op, checkpointId, stagingPath, "backup", stagingStatus);
        }

        ctx.sourceFs.renameFile(stagingPath, op.getBackupTargetPath(), false);
        targetStatus = getFileStatusIfPresent(ctx.sourceFs, op.getBackupTargetPath());
        if (targetStatus == null) {
            log.warn(
                    "Post-sync backup promotion target is absent after rename; operation will be retried: "
                            + "splitId={}, source={}, target={}, checkpointId={}",
                    op.getSplitId(),
                    maskUriUserInfo(op.getSourcePath()),
                    maskUriUserInfo(op.getBackupTargetPath()),
                    checkpointId);
            return OpCommitResult.FAILED_RETRYABLE;
        }
        if (!isOperationContentMatched(ctx, op, op.getBackupTargetPath(), targetStatus)) {
            log.warn(
                    "Post-sync backup promoted an unexpected target version; operation will be retried: "
                            + "splitId={}, source={}, target={}, checkpointId={}",
                    op.getSplitId(),
                    maskUriUserInfo(op.getSourcePath()),
                    maskUriUserInfo(op.getBackupTargetPath()),
                    checkpointId);
            return OpCommitResult.FAILED_RETRYABLE;
        }

        log.info(
                "Post-sync backup completed: source={}, target={}, checkpointId={}, "
                        + "capturedLen={}, capturedMtime={}",
                maskUriUserInfo(op.getSourcePath()),
                maskUriUserInfo(op.getBackupTargetPath()),
                checkpointId,
                op.getSourceLength(),
                op.getSourceModificationTime());
        return OpCommitResult.SUCCESS;

View on GitHub (pinned to cf67b549a7)

Solutions

Determine whether the source was rewritten concurrently; if so let the operation settle and re-check the versions in the log (expected vs actual len/mtime)
Remove the mismatched target file so a clean retry can promote the correct staged version
Enable/verify content fingerprinting (sourceContentFingerprint) so version checks are content-based instead of mtime-based, which is robust across filesystems
Check for connector version changes that altered the fingerprint computation between checkpoint save and restore

Example fix

null

Defensive patterns

Strategy: validation

Validate before calling

// Compare content fingerprints before trusting a backup target
String fp = sha256Hex(fs.open(targetPath));
if (!fp.equals(op.getSourceContentFingerprint())) {
    throw new IOException("Backup target version mismatch: " + targetPath);
}

Try / catch

try {
    verifyBackupContent(targetPath, expectedFingerprint);
} catch (IOException | NoSuchAlgorithmException e) {
    // treat as retryable mismatch; do not delete the source based on a bad target
}

Prevention

Enable content fingerprinting so checks are content-based rather than len/mtime-based
Prevent concurrent writers from mutating source files during post-sync operations
Keep connector versions consistent between checkpoint save and restore (fingerprint algorithm)

When it happens

Trigger: targetStatus is non-null after promotion but isOperationContentMatched() fails: the target's len/mtime differ from op.getSourceLength()/getSourceModificationTime(), or its SHA-256 fingerprint differs from op.getSourceContentFingerprint().

Common situations: The source file was modified by a writer after the operation captured its version, so the backup legitimately holds a different version; a previous attempt's differently-versioned file occupies the target path; fingerprint algorithm or encoding mismatch after a connector upgrade.

Understand the failure class

Background: Checksum mismatch errors: "checksum verification failed", "digest mismatch", "expected vs actual checksum" — what they mean and how to fix them — this error's family across 41 libraries.

Related errors

AI-assisted analysis of apache/seatunnel@cf67b549a7 (2026-09-10). Data as JSON: /api/errors/26e8bdf287362d20. Report an issue: GitHub.