apache/hadoop · error · IOException

The <version> section doesn't contain the onDiskVersion.

Error message

The <version> section doesn't contain the onDiskVersion.

What it means

The <version> section exists but contains no <onDiskVersion> child, which becomes FileSummary.onDiskVersion in the reconstructed image header. Without it the output fsimage would have no valid summary, so the tool refuses to continue.

Source

Thrown at hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/tools/offlineImageViewer/OfflineImageReconstructor.java:1692

   * Read the version tag which starts the XML file.
   */
  private void readVersion() throws IOException {
    try {
      expectTag("version", false);
    } catch (IOException e) {
      // Handle the case where <version> does not exist.
      // Note: fsimage XML files which are missing <version> are also missing
      // many other fields that oiv needs to accurately reconstruct the
      // fsimage.
      throw new IOException("No <version> section found at the top of " +
          "the fsimage XML.  This XML file is too old to be processed " +
          "by oiv.", e);
    }
    Node version = new Node();
    loadNodeChildren(version, "version fields");
    Integer onDiskVersion = version.removeChildInt("onDiskVersion");
    if (onDiskVersion == null) {
      throw new IOException("The <version> section doesn't contain " +
          "the onDiskVersion.");
    }
    Integer layoutVersion = version.removeChildInt("layoutVersion");
    if (layoutVersion == null) {
      throw new IOException("The <version> section doesn't contain " +
          "the layoutVersion.");
    }
    if (layoutVersion.intValue() !=
        NameNodeLayoutVersion.CURRENT_LAYOUT_VERSION) {
      throw new IOException("Layout version mismatch.  This oiv tool " +
          "handles layout version " +
          NameNodeLayoutVersion.CURRENT_LAYOUT_VERSION + ", but the " +
          "XML file has <layoutVersion> " + layoutVersion + ".  Please " +
          "either re-generate the XML file with the proper layout version, " +
          "or manually edit the XML file to be usable with this version " +
          "of the oiv tool.");
    }
    fileSummaryBld.setOndiskVersion(onDiskVersion);

View on GitHub (pinned to 2add963021)

Solutions

1. Add <onDiskVersion>1</onDiskVersion> inside <version> (the value oiv itself writes)
2. Check exact tag spelling/case - 'onDiskVersion'
3. If unsure of the value, regenerate the XML with a same-version oiv and diff the <version> block
4. Validate the version block before reconstructing

Example fix

<!-- before -->
<version><layoutVersion>-66</layoutVersion></version>
<!-- after -->
<version><onDiskVersion>1</onDiskVersion><layoutVersion>-66</layoutVersion></version>

# python: <version> must contain <onDiskVersion>
import xml.etree.ElementTree as ET

def version_block_ok(path):
    for ev, el in ET.iterparse(path, events=('end',)):
        if el.tag == 'version':
            return el.find('onDiskVersion') is not None
    return False

// catch the missing-onDiskVersion failure; copy the <version> block from
// a same-version oiv dump, delete partial output, re-run

When it happens

Trigger: A <version> element whose <onDiskVersion> child was omitted, renamed, or misspelled (exact tag required), typically in hand-edited or script-generated XML.

Common situations: Hand-built version headers copied incompletely; renaming fields for readability; XML trimmed by a transform that dropped 'uninteresting' fields.

Related errors

• The <version> section doesn't contain the layoutVersion.
• <snapshot> section was missing <id>
• <dirDiffEntry> contained no <inodeId> entry.
• <dirDiffEntry> contained no <count> entry.
• Expected to find <childrenSize> in <dirDiff> section.

AI-assisted analysis of apache/hadoop@2add963021 (2026-08-22). Data as JSON: /api/errors/305735bc14cd2ebc. Report an issue: GitHub.