There’s a handy feature in Moodle configuration called
$CFG->debugusers = '<moodle_user_ids>' that allows you to set certain user IDs to always see debug messages regardless fo the Site administration > Development > Debugging settings for the site. This can be a comma separated list of Moodle User Ids (from the user table). Set this in the
config.php or see
config-dist.php for more details.
Useful if you need to troubleshoot an error but don’t want to increase debug level for the entire system and catch messages for the other users in the system too.