apache/hadoop · error · UnsupportedOperationException

doesn't support getObjectTagging.

Error message

%s doesn't support getObjectTagging.

What it means

ObjectStorage.getTags has a default implementation that throws UnsupportedOperationException("<ClassName> doesn't support getObjectTagging."). Only the real TOS backend overrides it (TOS.getTags), so reading tags from the local FileStore backend or a custom implementation without an override fails with this error.

Solutions

1. Use the real TOS object storage when tag reads are required
2. Guard with a capability check (instanceof TOS or a supportsTags flag) before calling getTags
3. Override getTags in custom ObjectStorage implementations where the backend supports it
4. Degrade gracefully: skip tagging features when unsupported instead of failing

Example fix

// before
Map<String, String> tags = storage.getTags(key);

// after
Map<String, String> tags = (storage instanceof TOS)
    ? storage.getTags(key)
    : Collections.emptyMap();

private static boolean supportsTagging(ObjectStorage storage) {
  return storage instanceof org.apache.hadoop.fs.tosfs.object.tos.TOS;
}

try {
  Map<String, String> tags = storage.getTags(key);
} catch (UnsupportedOperationException e) {
  // backend without tagging support: degrade to empty tags
  return Collections.emptyMap();
}

When it happens

Trigger: Calling ObjectStorage.getTags(key) on a FileStore instance or a custom ObjectStorage plugin that did not override the default method, typically while porting tag-reading logic from the TOS backend to another backend.

Common situations: Tests running against the file-based backend; custom storage plugins that never implement tagging; code assuming every ObjectStorage supports object tagging.

Understand the failure class

Background: UnsupportedOperationException and "is not supported" errors: when a library deliberately refuses a call — this error's family across 30 libraries.

Related errors

• doesn't support putObjectTagging.
• Append is not supported by S3AFileSystem
• Cannot seek to a negative offset
• Expected checksum is
• Failed to delete objects, detail

AI-assisted analysis of apache/hadoop@2add963021 (2026-08-22). Data as JSON: /api/errors/ee9597b9f825c03a. Report an issue: GitHub.

Appendix: source

Thrown at hadoop-cloud-storage-project/hadoop-tos/src/main/java/org/apache/hadoop/fs/tosfs/object/ObjectStorage.java:336

   *
   * @param key     the key of the object key.
   * @param newTags the new tags to put.
   * @throws RuntimeException if key doesn't exist.
   */
  default void putTags(String key, Map<String, String> newTags) {
    throw new UnsupportedOperationException(
        this.getClass().getSimpleName() + " doesn't support putObjectTagging.");
  }

  /**
   * Get all attached tags of the object.
   *
   * @param key the key of the object.
   * @return map containing all tags.
   * @throws RuntimeException if key doesn't exist.
   */
  default Map<String, String> getTags(String key) {
    throw new UnsupportedOperationException(
        this.getClass().getSimpleName() + " doesn't support getObjectTagging.");
  }

  /**
   * Gets the object status for the given key.
   * It's different from {@link ObjectStorage#head(String)}, it returns object info if the key
   * exists or the prefix with value key exists.
   * <p>
   * There are three kinds of implementations:
   * <ul>
   *   <li>Uses the headObject API if the object storage support directory bucket and the requested
   *   bucket is a directory bucket, the object storage will return object directly if the file or
   *   dir exists, otherwise return null</li>
   *   <li>Uses getFileStatus API if the object storage support it, e.g. TOS. The object storage
   *   will return the object directly if the key or prefix exists, otherwise return null.</li>
   *   <li>If the object storage doesn't support above all cases, you have to try to headObject(key)
   *   at first, if the object doesn't exist, and then headObject(key + "/") later if the key
   *   doesn't end with '/', and if neither the new key doesn't exist, and then use listObjects API

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