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 ('b3ea263b4345d47e4d308fbb7dabfce4', -1, 1422384566, 1422384566, '3690f06e', -1, 0, 0)

Line : 189
File : sessions.php