There is a bug in the digest extension’s mailer that could cause some subscribers to receive duplicate digests. It can happen if a user selects a digest containing bookmarked topics only, then removed all his bookmarked topics in phpBB. This triggers an exception. An appropriate error is written to the admin log to document this unusual behavior. However the exception is coded in such a way as to stop digests from processing. No subsequent hours are processed.
Since the hour is not marked as completed the next attempt to run the mailer will trigger the error again. Duplicates can occur if the user is not the first one scheduled to receive digests for that hour. So if this user is the 10th user to get a digest for that hour, users 1 through 9 will get duplicates.
In addition this bug will keep any subsequent hours from being processed, creating a queue.
There is a workaround. Assuming Digests 3.0.6 is installed (the bug exists in earlier versions) the bug can be fixed by editing /ext/phpbbservices/digests/cron/task/digests.php. Around line 1420 look for this line of code:
$this->digest_exception = true;
and simply comment it out:
//$this->digest_exception = true;
This bug will be fixed in the next release.
