The following messages coming from the Joomla core may occasionally be seen, and can safely be ignored:

Warning: session_start(): Cannot send session cookie - headers already sent by (output started at /...../cli/issuetracker_imap.php:131) in /...../libraries/joomla/session/session.php on line 532

The above message is coming from the JTable Joomla code, when the composed new issue record is stored into the database. It seems to occur on the first (initial) cal to the JTable store routine only.

Warning: mysqli_ping(): Couldn't fetch mysqli in /...../libraries/joomla/database/database/mysqli.php on line 190

The above message is seen when exiting the cron task. The reason is not currently known, as we have not yet investigated the sequence of actions which cause the message to be generated.