pentaho/pentaho-kettle · error · KettleStepException

StringCut.Exception.FieldTypeNotString

Error message

StringCut.Exception.FieldTypeNotString

What it means

StringCut throws this KettleStepException in processRow() when an input field configured for cutting exists in the row but is not of type String. String Cut only operates on String fields; numeric, date, or boolean fields cannot be substring-cut.

Solutions

  1. Insert a 'Select Values' step before String Cut to convert the field to String
  2. Change the cut target to a field that is already String
  3. Adjust the upstream source/query to cast the column to text
  4. In the step dialog, re-select the field after the type fix

Example fix

// before
String Cut on field: amount (Integer)
// after
Select Values: amount -> String (meta type String, format), then String Cut on amount
Defensive patterns

Strategy: validation

Validate before calling

// validate types before execution
RowMetaInterface input = transMeta.getPrevStepFields(stepMeta);
for (String f : cutMeta.getFieldInStream()) {
  int idx = input.indexOfValue(f);
  if (idx >= 0 && input.getValueMeta(idx).getType() != ValueMetaInterface.TYPE_STRING) {
    throw new IllegalStateException("Field must be String: " + f);
  }
}

Try / catch

try {
  trans.execute(null);
  trans.waitUntilFinished();
} catch (KettleException e) {
  if (e.getMessage().contains("FieldTypeNotString")) {
    // insert a Select Values step converting the field to String, then re-run
  }
}

Prevention

When it happens

Trigger: At the first processed row when getInputRowMeta().getValueMeta(index).getType() != ValueMetaInterface.TYPE_STRING for one of the configured getFieldInStream() fields.

Common situations: Upstream step changed the field type (e.g. source column is Integer); missing a 'Field to string' / Select Values conversion before String Cut; schema drift after changing a database table.

Understand the failure class

Background: Type mismatch errors: IllegalArgumentException, TypeError and type guards across 150 open-source libraries — this error's family across 150 libraries.

Related errors

AI-assisted analysis of pentaho/pentaho-kettle@f3058517a1 (2026-09-13). Data as JSON: /api/errors/f63444b0a5300d23. Report an issue: GitHub.

Appendix: source

Thrown at engine/src/main/java/org/pentaho/di/trans/steps/stringcut/StringCut.java:139

    if ( first ) {
      first = false;
      // What's the format of the output row?
      data.outputRowMeta = getInputRowMeta().clone();
      data.inputFieldsNr = data.outputRowMeta.size();
      meta.getFields( getTransMeta().getBowl(), data.outputRowMeta, getStepname(), null, null, this, repository,
        metaStore );

      data.inStreamNrs = new int[meta.getFieldInStream().length];
      for ( int i = 0; i < meta.getFieldInStream().length; i++ ) {
        data.inStreamNrs[i] = getInputRowMeta().indexOfValue( meta.getFieldInStream()[i] );
        if ( data.inStreamNrs[i] < 0 ) {
          throw new KettleStepException( BaseMessages.getString( PKG, "StringCut.Exception.FieldRequired", meta
            .getFieldInStream()[i] ) );
        }

        // check field type
        if ( getInputRowMeta().getValueMeta( data.inStreamNrs[i] ).getType() != ValueMetaInterface.TYPE_STRING ) {
          throw new KettleStepException( BaseMessages.getString(
            PKG, "StringCut.Exception.FieldTypeNotString", meta.getFieldInStream()[i] ) );
        }
      }

      data.outStreamNrs = new String[meta.getFieldInStream().length];
      for ( int i = 0; i < meta.getFieldInStream().length; i++ ) {
        data.outStreamNrs[i] = environmentSubstitute( meta.getFieldOutStream()[i] );
      }

      data.cutFrom = new int[meta.getFieldInStream().length];
      data.cutTo = new int[meta.getFieldInStream().length];
      for ( int i = 0; i < meta.getFieldInStream().length; i++ ) {
        if ( Utils.isEmpty( environmentSubstitute( meta.getCutFrom()[i] ) ) ) {
          data.cutFrom[i] = 0;
        } else {
          data.cutFrom[i] = Const.toInt( environmentSubstitute( meta.getCutFrom()[i] ), 0 );
        }

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