apache/hadoop · error · UnsupportedOperationException

Cannot unsetErasureCodingPolicy through a symlink to a non-D

Error message

Cannot unsetErasureCodingPolicy through a symlink to a non-DistributedFileSystem: {} -> {}

What it means

Error "Cannot unsetErasureCodingPolicy through a symlink to a non-DistributedFileSystem: {} -> {}" thrown in apache/hadoop.

Source

Thrown at hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/DistributedFileSystem.java:3598

  public void unsetErasureCodingPolicy(final Path path) throws IOException {
    statistics.incrementWriteOps(1);
    storageStatistics.incrementOpCounter(OpType.UNSET_EC_POLICY);
    Path absF = fixRelativePart(path);
    new FileSystemLinkResolver<Void>() {
      @Override
      public Void doCall(final Path p) throws IOException {
        dfs.unsetErasureCodingPolicy(getPathName(p));
        return null;
      }

      @Override
      public Void next(final FileSystem fs, final Path p) throws IOException {
        if (fs instanceof DistributedFileSystem) {
          DistributedFileSystem myDfs = (DistributedFileSystem) fs;
          myDfs.unsetErasureCodingPolicy(p);
          return null;
        }
        throw new UnsupportedOperationException(
            "Cannot unsetErasureCodingPolicy through a symlink to a "
                + "non-DistributedFileSystem: " + path + " -> " + p);
      }
    }.resolve(this, absF);
  }

  /**
   * Verifies if the given policies are supported in the given cluster setup.
   * If not policy is specified checks for all enabled policies.
   * @param policyNames name of policies.
   * @return the result if the given policies are supported in the cluster setup
   * @throws IOException
   */
  public ECTopologyVerifierResult getECTopologyResultForPolicies(
      final String... policyNames) throws IOException {
    return dfs.getECTopologyResultForPolicies(policyNames);
  }

View on GitHub (pinned to 2add963021)

Solutions

1. Unset the erasure coding policy on the actual HDFS path.
2. Resolve symlinks; the operation requires a DistributedFileSystem target.

When it happens

Trigger: unsetErasureCodingPolicy is invoked through a symlink whose target is not a DistributedFileSystem, which does not support erasure coding policies.

Common situations: See trigger scenarios.

AI-assisted analysis of apache/hadoop@2add963021 (2026-08-22). Data as JSON: /api/errors/819a3ddd80e97a4e. Report an issue: GitHub.