apache/hadoop · error · IOException

FS image is being downloaded from another NN at txid {}

Error message

FS image is being downloaded from another NN at txid {}

What it means

Error "FS image is being downloaded from another NN at txid {}" thrown in apache/hadoop.

Source

Thrown at hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSImage.java:1165

  
  /**
   * Save the contents of the FS image to a new image file in each of the
   * current storage directories.
   */
  public synchronized void saveNamespace(FSNamesystem source, NameNodeFile nnf,
      Canceler canceler) throws IOException {
    assert editLog != null : "editLog must be initialized";
    LOG.info("Save namespace ...");
    storage.attemptRestoreRemovedStorage();

    boolean editLogWasOpen = editLog.isSegmentOpen();
    
    if (editLogWasOpen) {
      editLog.endCurrentLogSegment(true);
    }
    long imageTxId = getCorrectLastAppliedOrWrittenTxId();
    if (!addToCheckpointing(imageTxId)) {
      throw new IOException(
          "FS image is being downloaded from another NN at txid " + imageTxId);
    }
    try {
      try {
        saveFSImageInAllDirs(source, nnf, imageTxId, canceler);
        if (!source.isRollingUpgrade()) {
          updateStorageVersion();
        }
      } finally {
        if (editLogWasOpen) {
          editLog.startLogSegmentAndWriteHeaderTxn(imageTxId + 1,
              source.getEffectiveLayoutVersion());
          // Take this opportunity to note the current transaction.
          // Even if the namespace save was cancelled, this marker
          // is only used to determine what transaction ID is required
          // for startup. So, it doesn't hurt to update it unnecessarily.
          storage.writeTransactionIdFileToStorage(imageTxId + 1);
        }

View on GitHub (pinned to 2add963021)

Solutions

1. Wait for the in-progress image download from the other NameNode to complete before starting another transfer.
2. Restart the bootstrap if the transfer is stuck.

When it happens

Trigger: Saving the namespace while another NameNode is concurrently downloading an fsimage at the same txid (checkpoint conflict).

Common situations: See trigger scenarios.

AI-assisted analysis of apache/hadoop@2add963021 (2026-08-22). Data as JSON: /api/errors/152c977c21155a2e. Report an issue: GitHub.