pentaho/pentaho-kettle · error · KettleXMLException

AggregateRowsMeta.Exception.UnableToLoadStepInfo

AggregateRowsMeta.Exception.UnableToLoadStepInfo

Error message

AggregateRowsMeta.Exception.UnableToLoadStepInfo

What it means

AggregateRowsMeta.readData parses the step's XML definition (fields, names, renames, aggregate types) and throws KettleXMLException with this localized message when XML parsing fails. It signals that the step's metadata could not be loaded from a transformation file (.ktr).

Solutions

  1. Open the .ktr in Spoon and fix or re-create the Aggregate Rows step; re-save to regenerate valid XML.
  2. Check the <type> elements under the step's <fields> — they must be valid aggregate type names (sum, average, etc.).
  3. Compare the step XML against a known-good transformation saved with the same PDI version.
  4. Read the wrapped cause (getCause()) to distinguish XML parse errors from bad type values.

Example fix

<!-- before -->
<field><name>amount</name><rename>total</rename><type>summ</type></field>
<!-- after -->
<field><name>amount</name><rename>total</rename><type>sum</type></field>
Defensive patterns

Strategy: try-catch

Validate before calling

// Before loading a .ktr, sanity-check the step XML block
if (xml == null || !xml.contains("<fields>")) throw new IllegalArgumentException("AggregateRows step XML missing <fields> block");

Try / catch

try {
  meta.loadXML(stepNode, ...);
} catch (KettleXMLException e) {
  logger.error("AggregateRows XML invalid: " + e.getCause(), e);
  // fall back to re-creating the step or loading a backup .ktr
}

Prevention

When it happens

Trigger: loadXml is called on a malformed or hand-edited <fields> block in the step XML; getType receives an unrecognized aggregate type string; XMLHandler.getTagValue hits malformed XML causing a parse exception.

Common situations: A .ktr file edited by hand or by an external tool corrupting the step definition; opening a transformation saved by a newer/older PDI version with a changed XML schema; an invalid <type> value in the aggregate-rows step XML.

Understand the failure class

Background: JSON parse error: "Unexpected token" / "not valid JSON" / "failed to parse" — what JSON parsers are really complaining about — this error's family across 45 libraries.

Related errors

AI-assisted analysis of pentaho/pentaho-kettle@f3058517a1 (2026-09-13). Data as JSON: /api/errors/6d0db76072e467e9. Report an issue: GitHub.

Appendix: source

Thrown at plugins/aggregate-rows/core/src/main/java/org/pentaho/di/trans/steps/aggregaterows/AggregateRowsMeta.java:197

  private void readData( Node stepnode ) throws KettleXMLException {
    try {
      int i, nrfields;
      String type;

      Node fields = XMLHandler.getSubNode( stepnode, "fields" );
      nrfields = XMLHandler.countNodes( fields, "field" );

      allocate( nrfields );

      for ( i = 0; i < nrfields; i++ ) {
        Node fnode = XMLHandler.getSubNodeByNr( fields, "field", i );
        fieldName[i] = XMLHandler.getTagValue( fnode, "name" );
        fieldNewName[i] = XMLHandler.getTagValue( fnode, "rename" );
        type = XMLHandler.getTagValue( fnode, "type" );
        aggregateType[i] = getType( type );
      }
    } catch ( Exception e ) {
      throw new KettleXMLException( BaseMessages.getString(
        PKG, "AggregateRowsMeta.Exception.UnableToLoadStepInfo" ), e );
    }
  }

  @Override
  public void setDefault() {
    int i, nrfields;

    nrfields = 0;

    allocate( nrfields );

    for ( i = 0; i < nrfields; i++ ) {
      fieldName[i] = BaseMessages.getString( PKG, "AggregateRowsMeta.Fieldname.Label" );
      fieldNewName[i] = BaseMessages.getString( PKG, "AggregateRowsMeta.NewName.Label" );
      aggregateType[i] = TYPE_AGGREGATE_SUM;
    }
  }

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