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 ('51305f247188a6feb9591a5be9f709ca', -1, 1558938270, 1558938270, '6b17814d', 4, 0, 0)

Line : 187
File : sessions.php