pentaho/pentaho-kettle · error · KettleValueException

No data output data type was specified for new field

Error message

No data output data type was specified for new field [${fieldName}]

What it means

JavaScriptUtils.convertFromJs() converts a Rhino/Nashorn JS value to a Java object for a target field. When the target field's type is ValueMetaInterface.TYPE_NONE (no output data type specified), the switch has no conversion to apply and throws KettleValueException with this message. It means a JavaScript step's new output field lacks a declared data type.

Solutions

1. Set an explicit data type (String, Number, Date, BigNumber, Boolean, Binary) for the new field in the JavaScript step's output fields list.
2. In the script, explicitly type the field if using APIs that register fields, rather than leaving type NONE.
3. Review the transformation metadata (XML/ktr) to ensure <type> is not NONE/0 for that field.

Example fix

// before (step field config)
fieldName=outputField, type=None
// after
fieldName=outputField, type=String // (or Number/Date/BigNumber as required)

if (field.getType() == ValueMetaInterface.TYPE_NONE) {
  throw new KettleException("Output field '" + field.getName() + "' has no data type; set String/Number/Date/etc.");
}

try {
  Object result = JavaScriptUtils.convertFromJs(context, value, fieldName, classType);
} catch (KettleValueException e) {
  throw new KettleException("Set a data type for field " + fieldName + " in the JavaScript step fields grid", e);
}

When it happens

Trigger: A JavaScript step (Modified Java Script Value) defines a new output field whose ValueMeta has type TYPE_NONE — i.e. the field's type was left as 'None'/unspecified — and convertFromJs is invoked on that field.

Common situations: Transformation designer added a field in the script but never set the output field type in the step's fields grid (left as 'None'); upgrade or copy-paste dropped the type metadata; dynamic field creation without specifying type.

Understand the failure class

Background: "is required", "must be set", "missing required field": configuration validation errors across open-source libraries — this error's family across 36 libraries.

Related errors

• Can't convert a string to a date
• JavaScript conversion to BigNumber not implemented for
• Merge operation ' ' is not defined.
• PropertyOutput.Log.ErrorFindingField
• PropertyOutput.Log.FilenameInFieldEmpty

AI-assisted analysis of pentaho/pentaho-kettle@f3058517a1 (2026-09-13). Data as JSON: /api/errors/7ce17bcb2bce6326. Report an issue: GitHub.

Appendix: source

Thrown at engine/src/main/java/org/pentaho/di/core/util/JavaScriptUtils.java:66

        return jsToInteger( value, value.getClass() );

      case ValueMetaInterface.TYPE_STRING:
        return jsToString( value, classType );

      case ValueMetaInterface.TYPE_DATE:
        return jsToDate( value, classType );

      case ValueMetaInterface.TYPE_BOOLEAN:
        return value;

      case ValueMetaInterface.TYPE_BIGNUMBER:
        return jsToBigNumber( value, classType );

      case ValueMetaInterface.TYPE_BINARY:
        return Context.jsToJava( value, byte[].class );

      case ValueMetaInterface.TYPE_NONE:
        throw new KettleValueException( "No data output data type was specified for new field ["
          + fieldName + "]" );

      default:
        return Context.jsToJava( value, Object.class );
    }
  }

  public static Number jsToNumber( Object value, String classType ) {
    if ( classType.equalsIgnoreCase( JS_UNDEFINED ) ) {
      return null;
    } else if ( classType.equalsIgnoreCase( JS_NATIVE_JAVA_OBJ ) ) {
      try {
        // Is it a java Value class ?
        Value v = (Value) Context.jsToJava( value, Value.class );
        return v.getNumber();
      } catch ( Exception e ) {
        String string = Context.toString( value );
        return Double.parseDouble( Const.trim( string ) );

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