apache/hadoop · error · IOException

This is not a DFS

Error message

This is not a DFS

What it means

Error "This is not a DFS" thrown in apache/hadoop.

Source

Thrown at hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/SecondaryNameNode.java:457

          }
        });
        return b.booleanValue();
      } catch (InterruptedException e) {
        throw new RuntimeException(e);
      }
  }
  
  InetSocketAddress getNameNodeAddress() {
    return nameNodeAddr;
  }

  /**
   * Returns the Jetty server that the Namenode is listening on.
   */
  private URL getInfoServer() throws IOException {
    URI fsName = FileSystem.getDefaultUri(conf);
    if (!HdfsConstants.HDFS_URI_SCHEME.equalsIgnoreCase(fsName.getScheme())) {
      throw new IOException("This is not a DFS");
    }

    final String scheme = DFSUtil.getHttpClientScheme(conf);
    URI address = DFSUtil.getInfoServerWithDefaultHost(fsName.getHost(), conf,
        scheme);
    LOG.debug("Will connect to NameNode at " + address);
    return address.toURL();
  }

  /**
   * Start the web server.
   */
  @VisibleForTesting
  public void startInfoServer() throws IOException {
    final InetSocketAddress httpAddr = getHttpAddress(conf);
    final String httpsAddrString = conf.getTrimmed(
        DFSConfigKeys.DFS_NAMENODE_SECONDARY_HTTPS_ADDRESS_KEY,
        DFSConfigKeys.DFS_NAMENODE_SECONDARY_HTTPS_ADDRESS_DEFAULT);

View on GitHub (pinned to 2add963021)

Solutions

1. Run this checkpoint/geteditsize operation against a DFS (HDFS) nameservice, not a non-HDFS filesystem.

When it happens

Trigger: The SecondaryNameNode is pointed at a nameservice that is not a DistributedFileSystem.

Common situations: Misconfigured fs.defaultFS or namenode address pointing at a non-HDFS filesystem.

AI-assisted analysis of apache/hadoop@2add963021 (2026-08-22). Data as JSON: /api/errors/c7e51c02835d9e31. Report an issue: GitHub.