pentaho/pentaho-kettle · error · RuntimeException

The function call writeToLog requires 1 or 2 arguments.

Error message

The function call writeToLog requires 1 or 2 arguments.

What it means

writeToLog writes to the transformation log and accepts 1 argument (message, default log level) or 2 arguments (log level, message). A switch over ArgList.length falls through to default and throws RuntimeException for any other count.

Solutions

1. Combine message parts into one string: writeToLog('l', msg1 + msg2)
2. Use the 1-arg form writeToLog(msg) when default level is fine
3. Never pass a throwable; format it into the message

Example fix

// before
writeToLog(LogWriter.LOG_LEVEL_BASIC, 'x=', value, ' y=', other);
// after
writeToLog(LogWriter.LOG_LEVEL_BASIC, 'x=' + value + ' y=' + other);

// JS in Script step
if (arguments.length < 1 || arguments.length > 2) {
  throw new Error('writeToLog expects (msg) or (level, msg)');
}
writeToLog(level, msg);

// JS
function validWriteToLogArgs(args) {
  return args.length === 1 || args.length === 2;
}

try {
  writeToLog(LogWriter.LOG_LEVEL_BASIC, msg);
} catch (e) {
  // logging failed - fail safe, do not kill the transformation
}

When it happens

Trigger: Calling writeToLog() with zero arguments or with 3+ arguments, e.g. writeToLog(level, msg, detail) in a Script step.

Common situations: Passing varargs messages (writeToLog('a', 'b', 'c')); forgetting to concatenate message parts; porting from log4j-style calls with throwable argument.

Understand the failure class

Background: "missing required argument" and "the following required arguments were not provided": what required-argument errors mean and how to fix them — this error's family across 20 libraries.

Related errors

• The function call abs requires 1 argument.
• The function call appendToFile requires arguments.
• The function call ceil requires 1 argument.
• The function call getDigitsOnly requires 1 argument.
• The function call getFiscalDate requires 2 arguments.

AI-assisted analysis of pentaho/pentaho-kettle@f3058517a1 (2026-09-13). Data as JSON: /api/errors/159cef99874e3196. Report an issue: GitHub.

Appendix: source

Thrown at engine/src/main/java/org/pentaho/di/trans/steps/script/ScriptAddedFunctions.java:320

              scm.logBasic( strMessage );
            } else if ( strType.equals( "d" ) ) {
              scm.logDebug( strMessage );
            } else if ( strType.equals( "l" ) ) {
              scm.logDetailed( strMessage );
            } else if ( strType.equals( "e" ) ) {
              scm.logError( strMessage );
            } else if ( strType.equals( "m" ) ) {
              scm.logMinimal( strMessage );
            } else if ( strType.equals( "r" ) ) {
              scm.logRowlevel( strMessage );
            }
          }
        } catch ( Exception e ) {
          // Ignore errors
        }
        break;
      default:
        throw new RuntimeException( "The function call writeToLog requires 1 or 2 arguments." );
    }
  }

  private static boolean isUndefined( Object ArgList ) {
    return isUndefined( new Object[] { ArgList }, new int[] { 0 } );
  }

  private static boolean isUndefined( Object[] ArgList, int[] iArrToCheck ) {
    for ( int i = 0; i < iArrToCheck.length; i++ ) {
      if ( ArgList[iArrToCheck[i]].equals( undefinedValue ) ) {
        return true;
      }
    }
    return false;
  }

  private static boolean isNull( Object ArgList ) {
    return isNull( new Object[] { ArgList }, new int[] { 0 } );

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