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 ('83167f408e8dd5b6354d4292ef08bfe2', -1, 1464358109, 1464358109, '17140614', -1, 0, 0)

Line : 187
File : sessions.php