Hi @navmalik,
For your question:
[28-Jun-2019 03:57:37 UTC] PHP Fatal error: Uncaught Error: Call to a member function getFullName() on null in /home/zgz1shl6ysu9/public_html/ojs3121/lib/pkp/classes/submission/reviewAssignment/ReviewAssignmentDAO.inc.php:480
You probably have a data error, where a review assignment refers to a non-existent reviewer. You can identify these by running the following query in your database:
SELECT r.* FROM review_assignments r LEFT JOIN users u ON (r.reviewer_id = u.user_id) WHERE u.user_id IS NULL;
These entries can probably be deleted (but take a backup before you do so, just to be safe). I’m not sure where these entries could be coming from, so if you’re able to shed any light on that, please do.
Regards,
Alec Smecher
Public Knowledge Project Team