phpBB : Critical Error

Error creating new session

DEBUG MODE

SQL Error : 1062 Duplicate entry '-1' for key 'session_user_id'

INSERT INTO docttorrdiscluc_sessions (session_id, session_user_id, session_start, session_time, session_ip, session_page, session_logged_in, session_admin) VALUES ('d5c97256c0c7d822bbc4f661351e5a87', -1, 1547892926, 1547892926, '22cbd574', -8, 0, 0)

Line : 190
File : sessions.php