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 ('28044760c197e8c6a46dc1630d1bf1f5', -1, 1484894443, 1484894443, '36a19b06', 0, 0, 0)

Line : 189
File : sessions.php