What causes "Error adding values to row!" in pentaho/pentaho-kettle?

Inspect e.getCause() for the underlying MessagingException/IOException

pentaho/pentaho-kettle · error · KettleException

Error adding values to row!

Error message

Error adding values to row!

What it means

MailInput.getOneRow() wraps any Exception that occurs while converting the current email's fields into a Kettle output row. It is the generic catch-all of the row-building step: the message was fetched but row data extraction (fields, attachments info, body, rownr handling) failed.

Solutions

Inspect e.getCause() for the underlying MessagingException/IOException
Reduce fetched fields (disable body/attachment fields) to isolate the failing field
Reopen the connection/folder and rerun the transformation
Check message-specific problems by logging message number/subject before mapping

Example fix

// before
Object[] row = getOneRow(); // generic wrap hides real cause
// after
try {
  Object[] row = getOneRow();
} catch ( KettleException e ) {
  logError( "Row failed for message " + data.message.getMessageNumber() + ": ", e );
  setErrors( 1 );
  return null;
}

Defensive patterns

Strategy: try-catch

Try / catch

try {
  Object[] row = getOneRow();
} catch ( KettleException e ) {
  logError( "Error adding values to row: " + e.getCause(), e );
  setErrors( 1 );
  return null; // stop or skip depending on error handling policy
}

Prevention

Log message number/subject before mapping so failures are attributable
Limit fetched fields to what the protocol supports
Set the step's error handling to route bad rows to an error stream
Test transformations against real mailboxes containing edge-case emails

When it happens

Trigger: Any exception inside the per-message field mapping in getOneRow() (called from outputRowData): e.g. getMessage() content access fails, a field value cannot be converted, attachment retrieval throws.

Common situations: Unreadable message bodies on the server; MIME parsing errors on specific emails; step field configuration referencing content the protocol cannot fetch (e.g. body on POP3 with folder not opened); connection dropped mid-row.

Related errors

AI-assisted analysis of pentaho/pentaho-kettle@f3058517a1 (2026-09-13). Data as JSON: /api/errors/0a854c205b46b194. Report an issue: GitHub.

Appendix: source

Thrown at plugins/email-messages/impl/src/main/java/org/pentaho/di/trans/steps/mailinput/MailInput.java:236

      if ( isDebug() ) {
        logDebug( BaseMessages.getString( PKG, "MailInput.Log.FetchingMessage", data.mailConn.getEffectiveMessageNumber( message ) ) );
      }

      try {
        instance.parseToArray( r, message );
      } catch ( Exception e ) {
        String msg = e.getMessage();
        if ( meta.isStopOnError() ) {
          throw new KettleException( msg, e );
        } else {
          logError( msg, e );
        }
      }

      incrementLinesInput();
      data.rownr++;
    } catch ( Exception e ) {
      throw new KettleException( "Error adding values to row!", e );
    }

    return r;
  }

  private boolean openNextFolder() {
    try {
      if ( !meta.isDynamicFolder() ) {
        // static folders list
        // let's check if we fetched all values in list
        if ( data.folderenr >= data.folders.length ) {
          // We have fetched all folders
          if ( isDetailed() ) {
            logDetailed( BaseMessages.getString( PKG, "MailInput.Log.FinishedProcessing" ) );
          }
          return false;
        }
      } else {

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