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 ('a7b83e033e829c3e1f6dbb8a83a3e4a4', -1, 1467366569, 1467366569, '369ed119', -11, 0, 0)

Line : 201
File : sessions.php