phpBB : Critical Error

Error creating new session

DEBUG MODE

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

INSERT INTO r2ok_sessions (session_id, session_user_id, session_start, session_time, session_ip, session_page, session_logged_in, session_admin) VALUES ('3dbdd3a946e57509e482bdd0c3add26a', -1, 1524206173, 1524206173, '3650082c', 2, 0, 0)

Line : 187
File : sessions.php