pentaho/pentaho-kettle · error

The function call getProcessCount requires 1 argument.

Error message

The function call getProcessCount requires 1 argument.

What it means

Arity guard for getProcessCount in the Rhino-based script-values step: it takes exactly one argument, a letter selecting which counter to return (i=input, o=output, r=read, u=updated, w=written, e=rejected). Any other count throws; note that an unrecognized letter silently returns 0 instead.

Solutions

1. Pass the step name: getProcessCount('Step name').
2. Confirm the step name string is not empty before calling.
3. Use the actual step label exactly as it appears on the transformation canvas.

Example fix

// before
var c = getProcessCount();
// after
var c = getProcessCount('Filter rows');

var stepName = 'Filter rows';
if (typeof stepName !== 'string' || stepName.length === 0) {
  throw 'getProcessCount needs a non-empty step name';
}
var count = getProcessCount(stepName);

When it happens

Trigger: Calling getProcessCount() with an empty argument list in a Modified Java Script Value step.

Common situations: Exploring the available script functions and invoking without arguments; a variable holding the step name was deleted leaving a bare call.

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 floor requires 1 argument.
• The function call getDayNumber requires 2 arguments.

AI-assisted analysis of pentaho/pentaho-kettle@f3058517a1 (2026-09-13). Data as JSON: /api/errors/8d3d772234fc925d. Report an issue: GitHub.

Appendix: source

Thrown at engine/src/main/java/org/pentaho/di/trans/steps/scriptvalues_mod/ScriptValuesAddedFunctions.java:291

        } else if ( strType.equals( "o" ) ) {
          return scm.getLinesOutput();
        } else if ( strType.equals( "r" ) ) {
          return scm.getLinesRead();
        } else if ( strType.equals( "u" ) ) {
          return scm.getLinesUpdated();
        } else if ( strType.equals( "w" ) ) {
          return scm.getLinesWritten();
        } else if ( strType.equals( "e" ) ) {
          return scm.getLinesRejected();
        } else {
          return 0;
        }
      } catch ( Exception e ) {
        // throw Context.reportRuntimeError(e.toString());
        return 0;
      }
    } else {
      throw Context.reportRuntimeError( "The function call getProcessCount requires 1 argument." );
    }
  }

  public static void writeToLog( Context actualContext, Scriptable actualObject, Object[] ArgList,
    Function FunctionContext ) {

    switch ( ArgList.length ) {
      case 1:
        try {
          if ( !isNull( ArgList ) && !isUndefined( ArgList ) ) {
            Object scmO = actualObject.get( "_step_", actualObject );
            ScriptValuesMod scm = (ScriptValuesMod) Context.jsToJava( scmO, ScriptValuesMod.class );
            String strMessage = Context.toString( ArgList[0] );
            scm.logDebug( strMessage );
          }
        } catch ( Exception e ) {
          // Ignore errors
        }

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