What causes "The function call decode is not valid : " in pentaho/pentaho-kettle?

Guard input values with a null check before calling decode (e.g. `value == null ? def : decode(value, ...)`)

pentaho/pentaho-kettle · error · RhinoRuntimeError

The function call decode is not valid :

Error message

The function call decode is not valid :

What it means

The `decode()` ScriptValuesMod function wraps its whole comparison logic in a try/catch and re-throws any exception (regex-free string comparison failures, invalid types, Context conversion errors) as this runtime error with the original message appended. The message shown was empty, meaning the underlying exception had a null/blank getMessage().

Solutions

Guard input values with a null check before calling decode (e.g. `value == null ? def : decode(value, ...)`)
Convert fields to strings explicitly before passing them: decode(str(value), ...)
Rebuild the message by enabling the underlying exception: log ArgList types before calling decode to find the offending value

Example fix

// before
var out = decode(fieldA, 'x', 1, 0);
// after
var out = (fieldA == null) ? 0 : decode(Context.toString(fieldA), 'x', 1, 0);

Defensive patterns

Strategy: type-guard

Validate before calling

if (value == null) { logError('decode input is null'); } else { var out = decode(String(value), 'x', 1, 0); }

Type guard

function isSafeForDecode(v) { return v !== null && v !== undefined; }

Try / catch

try {
  var out = decode(v, 'x', 1, 0);
} catch (e) {
  if (String(e).indexOf('decode is not valid') !== -1) { out = 0; } else { throw e; }
}

Prevention

Null-guard every field read from the row before decode
Coerce numeric fields to strings before comparison
Test the JavaScript step with sample rows including nulls

When it happens

Trigger: Any runtime exception inside decode's comparison loop: null values being compared via equals without guarding, incompatible object types passed as ArgList, or Context.toString conversion failures where e.getMessage() returns null.

Common situations: Passing null fields from a previous step into decode(); passing non-string/non-comparable objects (e.g. binary, Number vs String) as search values; Kettle field values that are null on the first row.

Understand the failure class

Background: "Must be a positive integer", "Invalid value", "Unsupported": the invalid-argument-value error family, when a library rejects the value you pass — this error's family across 35 libraries.

Related errors

AI-assisted analysis of pentaho/pentaho-kettle@f3058517a1 (2026-09-13). Data as JSON: /api/errors/2ea52df1f4033fc8. Report an issue: GitHub.

Appendix: source

Thrown at engine/src/main/java/org/pentaho/di/trans/steps/scriptvalues_mod/ScriptValuesAddedFunctions.java:1537

        } else if ( isUndefined( ArgList, new int[] { 0, 1 } ) ) {
          return Context.getUndefinedValue();
        }
        Object objToCompare = ArgList[0];
        for ( int i = 1; i < ArgList.length - 1; i = i + 2 ) {
          if ( ArgList[i].equals( objToCompare ) ) {
            return ArgList[i + 1];
          }
        }
        if ( ArgList.length % 2 == 0 ) {
          return ArgList[ArgList.length - 1];
        } else {
          return objToCompare;
        }
      } else {
        throw Context.reportRuntimeError( "The function call decode requires more than 1 argument." );
      }
    } catch ( Exception e ) {
      throw Context.reportRuntimeError( "The function call decode is not valid : " + e.getMessage() );
    }
  }

  public static String replace( Context actualContext, Scriptable actualObject, Object[] ArgList,
    Function FunctionContext ) {
    try {
      if ( ArgList.length >= 2 && ( ArgList.length - 1 ) % 2 == 0 ) {
        if ( isNull( ArgList, new int[] { 0, 1 } ) ) {
          return null;
        } else if ( isUndefined( ArgList, new int[] { 0, 1 } ) ) {
          return (String) Context.getUndefinedValue();
        }
        String objForReplace = Context.toString( ArgList[0] );
        for ( int i = 1; i < ArgList.length - 1; i = i + 2 ) {
          objForReplace =
            objForReplace.replaceAll( Context.toString( ArgList[i] ), Context.toString( ArgList[i + 1] ) );
        }
        return objForReplace;

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