pentaho/pentaho-kettle · error · KettleException

MailConnection.Error.FetchingMessages

Error message

MailConnection.Error.FetchingMessages

What it means

MailConnection.fetchNext() wraps any exception from indexing this.messages[getMessageNr()] into a KettleException with key MailConnection.Error.FetchingMessages. The typical cause is an ArrayIndexOutOfBoundsException when the internal counter runs past the end of the fetched message array, or a Message has been expunged.

Solutions

  1. Stop iterating when getMessageNr() >= getMessagesCount() instead of relying on fetchNext() to throw.
  2. Use the library's iteration loop (nextMessage/hasMore style helpers) rather than manual index arithmetic.
  3. Re-fetch the message list after external deletions, then restart the iteration.

Example fix

// before
while (true) {
  connection.fetchNext(); // eventually out of bounds
  process(connection.getMessage());
}
// after
for (int i = 0; i < connection.getMessagesCount(); i++) {
  connection.fetchNext();
  process(connection.getMessage());
}
Defensive patterns

Strategy: validation

Validate before calling

if (connection.getMessagesCount() == 0 || connection.getMessageNr() >= connection.getMessagesCount()) { return; // nothing left to fetch }

Try / catch

try { connection.fetchNext(); } catch (KettleException e) { logError("Fetch failed at index " + connection.getMessageNr(), e); break; }

Prevention

When it happens

Trigger: Calling fetchNext() more times than there are messages in the folder (getMessageNr() >= messages.length), or after the folder's messages were expunged so the array/sequence numbers are stale.

Common situations: Loop boundary off-by-one in a custom job/script driving MailConnection directly; another client deleted messages mid-scan making the cached array stale; folder re-opened and messages refetched with a different count.

Related errors

AI-assisted analysis of pentaho/pentaho-kettle@f3058517a1 (2026-09-13). Data as JSON: /api/errors/c0a1c38f789e3e46. Report an issue: GitHub.

Appendix: source

Thrown at plugins/email-messages/impl/src/main/java/org/pentaho/di/job/entries/getpop/MailConnection.java:1238

  private void updateMessageNr() {
    this.messagenr++;
  }

  private int getMessageNr() {
    return this.messagenr;
  }

  /**
   * Get next message.
   *
   * @throws KettleException
   */
  public void fetchNext() throws KettleException {
    updateMessageNr();
    try {
      this.message = this.messages[getMessageNr()];
    } catch ( Exception e ) {
      throw new KettleException( BaseMessages.getString( PKG, "MailConnection.Error.FetchingMessages" ), e );
    }
  }

  /**
   * Returns the current message.
   *
   * @return current message
   */
  public Message getMessage() {
    return this.message;
  }

  /**
   * Returns the number of messages.
   *
   * @return messages count
   */
  public int getMessagesCount() {

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