There are errors in the header when going to the notification settings

[phpBB Debug] PHP Notice: in file [ROOT]/includes/notification/method/jabber.php on line 56: Undefined index: jabber
[phpBB Debug] PHP Notice: in file [ROOT]/includes/notification/method/jabber.php on line 56: Undefined index: jabber
[phpBB Debug] PHP Warning: in file [ROOT]/includes/functions.php on line 5395: Cannot modify header information - headers already sent by (output started at [ROOT]/includes/functions.php:4224)
[phpBB Debug] PHP Warning: in file [ROOT]/includes/functions.php on line 5397: Cannot modify header information - headers already sent by (output started at [ROOT]/includes/functions.php:4224)
[phpBB Debug] PHP Warning: in file [ROOT]/includes/functions.php on line 5398: Cannot modify header information - headers already sent by (output started at [ROOT]/includes/functions.php:4224)
[phpBB Debug] PHP Warning: in file [ROOT]/includes/functions.php on line 5399: Cannot modify header information - headers already sent by (output started at [ROOT]/includes/functions.php:4224)