apache/hadoop · error · IOException

Expected tag end event for {expected}, but got tag end event

Error message

Expected tag end event for {expected}, but got tag end event for {tag}

What it means

After expectTagEnd receives an END_ELEMENT it checks that the closing tag's local name equals the expected literal (the check is skipped for [...] group names). A different closing name means the document's end tags do not line up with the element the reconstructor is closing; some StAX configurations pass mismatched end tags through as events rather than raising XMLStreamException, which is how this state becomes reachable.

Source

Thrown at hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/tools/offlineImageViewer/OfflineImageReconstructor.java:243

        if (LOG.isTraceEnabled()) {
          LOG.trace("Skipping XMLEvent of type " +
              ev.getEventType() + "(" +  ev + ")");
        }
        break;
      }
    }
  }

  private void expectTagEnd(String expected) throws IOException {
    XMLEvent ev = expectTag(expected, true);
    if (ev.getEventType() != XMLStreamConstants.END_ELEMENT) {
      throw new IOException("Expected tag end event for " + expected +
            ", but got: " + ev);
    }
    if (!expected.startsWith("[")) {
      String tag = ev.asEndElement().getName().getLocalPart();
      if (!tag.equals(expected)) {
        throw new IOException("Expected tag end event for " + expected +
        ", but got tag end event for " + tag);
      }
    }
  }

  private static class Node {
    private static final String EMPTY = "";
    HashMap<String, LinkedList<Node>> children;
    String val = EMPTY;

    void addChild(String key, Node node) {
      if (children == null) {
        children = new HashMap<>();
      }
      LinkedList<Node> cur = children.get(key);
      if (cur == null) {
        cur = new LinkedList<>();
        children.put(key, cur);

View on GitHub (pinned to 2add963021)

Solutions

Rename the closing tag to match its start tag - the message names both
Run xmllint --noout first; it rejects most mismatched end tags before ReverseXML runs
Regenerate the XML instead of patching tag names

Example fix

<!-- before -->
<inode><id>16386</id></file>

<!-- after -->
<inode><id>16386</id></inode>

Defensive patterns

Strategy: validation

Validate before calling

xmllint --noout fsimage.xml || { echo 'fix the reported mismatched/unclosed tags first'; exit 1; }

Prevention

Rename start and end tags together (regex on the pair, not single names)
Reject hand-spliced subtrees unless their tags round-trip through xmllint
Prefer regenerating over renaming tags

When it happens

Trigger: An element closed with the wrong name - e.g. </file> where </inode> was required - after a start tag was renamed without its closer, or a subtree spliced from another dump keeping its original closing tags.

Common situations: Find/replace renames that hit only one tag of the pair; hand-built sections assembled by copying fragments.

Related errors

AI-assisted analysis of apache/hadoop@2add963021 (2026-08-22). Data as JSON: /api/errors/9ae5a359a284a900. Report an issue: GitHub.