apache/hadoop · error · HadoopIllegalArgumentException

"Invalid protocol: " + protocol

Error message

"Invalid protocol: " + protocol

What it means

After -protocol consumes its single parameter, LogLevel.isValidProtocol accepts only the exact lowercase strings 'http' and 'https' (PROTOCOL_HTTP/PROTOCOL_HTTPS, compared with equals). Anything else — 'HTTP', 'Http', 'hdfs', 'hadooprpc' — throws HadoopIllegalArgumentException('Invalid protocol: ...'). The scheme also decides which client path runs: doGetLevel/doSetLevel use AuthenticatedURL and SSLFactory accordingly.

Source

Thrown at hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/log/LogLevel.java:224

      return index+4;
    }

    private int parseProtocolArgs(String[] args, int index) throws
        HadoopIllegalArgumentException {
      // make sure only -protocol is specified
      if (protocol != null) {
        throw new HadoopIllegalArgumentException(
            "Redundant -protocol command");
      }
      // check number of arguments is sufficient
      if (index+1 >= args.length) {
        throw new HadoopIllegalArgumentException(
            "-protocol needs one parameter");
      }
      // check protocol is valid
      protocol = args[index+1];
      if (!isValidProtocol(protocol)) {
        throw new HadoopIllegalArgumentException(
            "Invalid protocol: " + protocol);
      }
      return index+2;
    }

    /**
     * Send HTTP/HTTPS request to get log level.
     *
     * @throws HadoopIllegalArgumentException if arguments are invalid.
     * @throws Exception if unable to connect
     */
    private void doGetLevel() throws Exception {
      process(protocol + "://" + hostName + "/logLevel?log=" + className);
    }

    /**
     * Send HTTP/HTTPS request to set log level.
     *

View on GitHub (pinned to 2add963021)

Solutions

1. Use exactly 'http' or 'https' in lowercase.
2. Normalize in scripts: SCHEME=$(echo "$SCHEME" | tr 'A-Z' 'a-z') and strip whitespace.
3. If the daemon's admin UI is SSL-enabled, remember it must be https with the proper SSLFactory setup on the daemon side.

Example fix

# before
hadoop loglevel -getlevel nn:9871 cls -protocol HTTPS

# after
hadoop loglevel -getlevel nn:9871 cls -protocol https

if (!LogLevel.isValidProtocol(scheme)) {
  throw new HadoopIllegalArgumentException(
      "protocol must be exactly 'http' or 'https' (lowercase), got: " + scheme);
}
// or reuse the public helper directly: LogLevel.isValidProtocol(args[i+1])

boolean isSupportedLogLevelProtocol(String s) {
  return s != null && ("http".equals(s) || "https".equals(s));
}

When it happens

Trigger: '-protocol HTTP' or '-protocol Https' (case mismatch); '-protocol hdfs' or other scheme names; values with trailing whitespace or quotes from shell expansion.

Common situations: Uppercase scheme habits from URLs/browsers; scripts passing a generic $SCHEME variable used for other tools; quoting artifacts from wrappers.

Related errors

• Redundant -protocol command
• -protocol needs one parameter
• Expect either -getlevel or -setlevel
• No arguments specified
• "Unexpected argument " + args[nextArgIndex]

AI-assisted analysis of apache/hadoop@2add963021 (2026-08-22). Data as JSON: /api/errors/009e0d1f7ba34ae8. Report an issue: GitHub.