phpBB : Critical Error

Error creating new session

DEBUG MODE

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

INSERT INTO forum_sessions (session_id, session_user_id, session_start, session_time, session_ip, session_page, session_logged_in, session_admin) VALUES ('e5ac00a1c3b6a6228d69056da8c27a61', -1, 1540100774, 1540100774, '36a14d1e', -4, 0, 0)

Line : 187
File : sessions.php