pentaho/pentaho-kettle · error · RuntimeException

The function call appendToFile requires arguments.

Error message

The function call appendToFile requires arguments.

What it means

Arity guard in ScriptAddedFunctions.appendToFile: the script invoked the function with a null/undefined or empty argument list, but it needs (filename, content) to open the FileOutputStream in append mode and write the bytes. The guard fires before any file is touched.

Solutions

1. Pass the filename (and content) explicitly: appendToFile(filename, content)
2. Guard undefined variables in JS before the call
3. Wrap in try/catch and fall back to a default message

Example fix

// before
appendToFile();
// after
appendToFile('/tmp/out.log', 'entry: ' + value);

// JS in Script step
if (arguments.length === 0) {
  throw new Error('appendToFile needs at least a filename');
}
appendToFile(filename, content);

// JS
function hasArgs(args) {
  return args.length > 0;
}

try {
  appendToFile(file, msg);
} catch (e) {
  Logger.logError('appendToFile failed: ' + e.message);
}

When it happens

Trigger: Calling appendToFile() with no arguments from a Script step; a variable holding the content being undefined so the dynamically-built argument list is empty.

Common situations: Logging scripts where the message variable is undefined/null and got dropped; generated scripts with conditional argument construction that skipped all args.

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

AI-assisted analysis of pentaho/pentaho-kettle@f3058517a1 (2026-09-13). Data as JSON: /api/errors/471cb3a434fb1373. Report an issue: GitHub.

Appendix: source

Thrown at engine/src/main/java/org/pentaho/di/trans/steps/script/ScriptAddedFunctions.java:206

      throw new RuntimeException( e.toString() );
    }
  }

  public static void appendToFile( ScriptEngine actualContext, Bindings actualObject, Object[] ArgList,
    Object FunctionContext ) {

    if ( !isNull( ArgList ) && !isUndefined( ArgList ) ) {
      try {
        FileOutputStream file = new FileOutputStream( (String) ArgList[0], true );
        DataOutputStream out = new DataOutputStream( file );
        out.writeBytes( (String) ArgList[1] );
        out.flush();
        out.close();
      } catch ( Exception er ) {
        throw new RuntimeException( er.toString() );
      }
    } else {
      throw new RuntimeException( "The function call appendToFile requires arguments." );
    }
  }

  public static Object getFiscalDate( ScriptEngine actualContext, Bindings actualObject, Object[] ArgList,
    Object FunctionContext ) {

    if ( ArgList.length == 2 ) {
      try {
        if ( isNull( ArgList ) ) {
          return null;
        } else if ( isUndefined( ArgList ) ) {
          return undefinedValue;
        }
        java.util.Date dIn = (java.util.Date) ArgList[0];
        Calendar startDate = Calendar.getInstance();
        Calendar fisStartDate = Calendar.getInstance();
        Calendar fisOffsetDate = Calendar.getInstance();
        startDate.setTime( dIn );

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