apache/hadoop · error · UnsupportedOperationException

Unsupported Credentials Flavor

Error message

Unsupported Credentials Flavor 

What it means

Error "Unsupported Credentials Flavor " thrown in apache/hadoop.

Source

Thrown at hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/oncrpc/security/Credentials.java:42

/**
 * Base class for all credentials. Currently we only support 3 different types
 * of auth flavors: AUTH_NONE, AUTH_SYS, and RPCSEC_GSS.
 */
public abstract class Credentials extends RpcAuthInfo {
  public static final Logger LOG = LoggerFactory.getLogger(Credentials.class);

  public static Credentials readFlavorAndCredentials(XDR xdr) {
    AuthFlavor flavor = AuthFlavor.fromValue(xdr.readInt());
    final Credentials credentials;
    if(flavor == AuthFlavor.AUTH_NONE) {
      credentials = new CredentialsNone();
    } else if(flavor == AuthFlavor.AUTH_SYS) {
      credentials = new CredentialsSys();
    } else if(flavor == AuthFlavor.RPCSEC_GSS) {
      credentials = new CredentialsGSS();
    } else {
      throw new UnsupportedOperationException("Unsupported Credentials Flavor "
          + flavor);
    }
    credentials.read(xdr);
    return credentials;
  }

  /**
   * Write AuthFlavor and the credentials to the XDR
   * @param cred credentials
   * @param xdr XDR message
   */
  public static void writeFlavorAndCredentials(Credentials cred, XDR xdr) {
    if (cred instanceof CredentialsNone) {
      xdr.writeInt(AuthFlavor.AUTH_NONE.getValue());
    } else if (cred instanceof CredentialsSys) {
      xdr.writeInt(AuthFlavor.AUTH_SYS.getValue());
    } else if (cred instanceof CredentialsGSS) {
      xdr.writeInt(AuthFlavor.RPCSEC_GSS.getValue());

View on GitHub (pinned to 2add963021)

Solutions

1. Use a supported RPC credentials flavor (AUTH_NONE, AUTH_SYS/AUTH_UNIX, or RPCSEC_GSS as supported by the server).
2. Check the client configuration for the authentication flavor and correct unsupported or misspelled values.
3. Upgrade the client if it attempts to use a flavor this Hadoop version does not implement.

When it happens

Trigger: Thrown at hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/oncrpc/security/Credentials.java:42 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of apache/hadoop@2add963021 (2026-08-22). Data as JSON: /api/errors/a840a488861c6a1c. Report an issue: GitHub.