pentaho/pentaho-kettle · error · KettleException

XML does not allow empty strings for element names.

Error message

XML does not allow empty strings for element names.

What it means

The AddXML step builds an XML document where each selected field becomes an element (or attribute). When the configured element name is empty, the code first falls back to using the field name; if the field name is also null/empty, no valid XML element name exists, so the step throws this KettleException. XML spec forbids empty element names.

Solutions

1. Open the AddXML step dialog and set a valid 'Element name' for every field in the 'Fields to XML' table
2. Ensure the incoming stream field has a non-empty name so the fallback (element = fieldname) succeeds
3. Validate the AddXMLMeta outputFields in code before running the transformation
4. Re-import/re-save the transformation metadata if the field definitions came from a corrupt repository export

Example fix

// before
OutputField f = new OutputField(); // elementName=null, fieldName=null
fields.add(f);
// after
OutputField f = new OutputField("customer", "customer", false);
f.setElementName("customer");
fields.add(f);

for (XMLField f : meta.getOutputFields()) {
  String el = f.getElementName();
  if (el == null || el.isEmpty()) {
    String fb = f.getName();
    if (fb == null || fb.isEmpty())
      throw new IllegalArgumentException("Field with no element name and no field name in AddXML step");
  }
}

boolean hasValidElementName(XMLField f) {
  return (f.getElementName() != null && !f.getElementName().isEmpty())
      || (f.getName() != null && !f.getName().isEmpty());
}

try { step.processRow(); } catch (KettleException ke) {
  if ("XML does not allow empty strings for element names.".equals(ke.getMessage())) {
    logError("AddXML field missing element name: fix step field table");
  }
}

When it happens

Trigger: processRow encounters an outputField whose XML 'Field to XML' element name is blank AND the source stream field name is also empty — e.g. a field row with no name and no element name configured in the step dialog.

Common situations: Step metadata imported from an incomplete XML/repository definition; renamed/deleted upstream fields leaving the field name empty; programmatically built AddXMLMeta with OutputField having null elementName and fieldName.

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

• The tablename is not defined (empty)
• AccessInput.Exception.CouldnotFindField
• AccessInput.Log.NoField
• AddSequence.Exception.NoSpecifiedMethod
• AddSequenceMeta.Exception.ErrorLoadingStepInfo

AI-assisted analysis of pentaho/pentaho-kettle@f3058517a1 (2026-09-13). Data as JSON: /api/errors/ef2ebf10d5e02f65. Report an issue: GitHub.

Appendix: source

Thrown at plugins/xml/core/src/main/java/org/pentaho/di/trans/steps/addxml/AddXML.java:117

    Document xmldoc = getDomImplentation().createDocument( null, meta.getRootNode(), null );
    Element root = xmldoc.getDocumentElement();
    for ( int i = 0; i < meta.getOutputFields().length; i++ ) {
      XMLField outputField = meta.getOutputFields()[i];
      String fieldname = outputField.getFieldName();

      ValueMetaInterface v = getInputRowMeta().getValueMeta( data.fieldIndexes[i] );
      Object valueData = r[data.fieldIndexes[i]];

      if ( !meta.isOmitNullValues() || !v.isNull( valueData ) ) {
        String value = formatField( v, valueData, outputField );

        String element = outputField.getElementName();
        if ( element == null || element.length() == 0 ) {
          element = fieldname;
        }

        if ( element == null || element.length() == 0 ) {
          throw new KettleException( "XML does not allow empty strings for element names." );
        }
        if ( outputField.isAttribute() ) {
          String attributeParentName = outputField.getAttributeParentName();

          Element node;

          if ( attributeParentName == null || attributeParentName.length() == 0 ) {
            node = root;
          } else {
            NodeList nodelist = root.getElementsByTagName( attributeParentName );
            if ( nodelist.getLength() > 0 ) {
              node = (Element) nodelist.item( 0 );
            } else {
              node = root;
            }
          }

          node.setAttribute( element, value );

View on GitHub (pinned to f3058517a1)