phpBB : Critical Error

Error creating new session

DEBUG MODE

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

INSERT INTO phpbb_sessions (session_id, session_user_id, session_start, session_time, session_ip, session_page, session_logged_in, session_admin) VALUES ('16c7e65e6929c87e8e13d59322edb79c', -1, 1542611594, 1542611594, '36ea0daf', 7, 0, 0)

Line : 187
File : sessions.php