pentaho/pentaho-kettle · error · KettleException

AvroInput.Error.NoFieldPathsDefined

AvroInput.Error.NoFieldPathsDefined

Error message

AvroInput.Error.NoFieldPathsDefined

What it means

AvroNestedReader.init requires at least one field path (the fields to read from the Avro records). If m_normalFields is null or empty, no output columns would be produced, so init throws a KettleException with the localized message 'AvroInput.Error.NoFieldPathsDefined'.

Solutions

  1. Add field path mappings in the Avro Input step dialog (select fields from the schema)
  2. Verify the step's field list survived save/load (re-open and re-save the step)
  3. If building metadata in code, populate fields before init

Example fix

// before
meta.setFieldPaths(new String[0]); // no fields
// after
meta.setFieldPaths(new String[]{ "$.id", "$.name" });
Defensive patterns

Strategy: validation

Validate before calling

if (meta.getFields() == null || meta.getFields().isEmpty()) {
  throw new KettleException("Avro Input step must define at least one field path before running");
}

Try / catch

try {
  nestedReader.init();
} catch (KettleException e) {
  logError("No field paths configured: " + e.getMessage());
  setErrors(1);
}

Prevention

When it happens

Trigger: Calling init() when no Avro input fields / field paths were configured on the step metadata.

Common situations: Running a transformation where the Avro Input step has an empty 'fields' mapping list; fields lost after XML/repository load failure; programmatic StepMeta setup without addField calls.

Understand the failure class

Background: "must not be empty", "cannot be empty" — required-field validation errors across open-source libraries — this error's family across 41 libraries.

Related errors

AI-assisted analysis of pentaho/pentaho-kettle@f3058517a1 (2026-09-13). Data as JSON: /api/errors/d4f7a9b7751914d1. Report an issue: GitHub.

Appendix: source

Thrown at plugins/avro-format/core/src/main/java/org/pentaho/di/trans/steps/avro/input/AvroNestedReader.java:213

  protected AvroToPdiConverter m_avroToPdiConverter;

  /**
   * Factory for obtaining a decoder
   */
  protected DecoderFactory m_factory;

  //protected static Class<?> PKG = AvroInputMeta.class;
  protected static Class<?> PKG = AvroNestedReader.class;


  protected void init() throws KettleException {
    if ( m_schemaToUse != null ) {
      m_avroToPdiConverter = new AvroToPdiConverter( m_schemaToUse );
      initTopLevelStructure( m_schemaToUse, true );
    }

    if ( m_normalFields == null || m_normalFields.size() == 0 ) {
      throw new KettleException( BaseMessages.getString( PKG, "AvroInput.Error.NoFieldPathsDefined" ) );
    }

    m_expansionHandler = checkFieldPaths( m_normalFields, m_outputRowMeta );

    int killmeIndex = 0;
    for ( AvroInputField f : m_normalFields ) {
      //bypass this for now: int outputIndex = m_outputRowMeta.indexOfValue( f.getPentahoFieldName() );
      int outputIndex = killmeIndex++;
      fieldInit( f, outputIndex );
    }

    if ( m_expansionHandler != null ) {
      m_expansionHandler.init();
    }
    m_factory = new DecoderFactory();
  }

  /**

View on GitHub (pinned to f3058517a1)