phpBB : Critical Error

Error creating new session

DEBUG MODE

SQL Error : 1062 Duplicate entry '-1' for key 2

INSERT INTO mex2mex_sessions (session_id, session_user_id, session_start, session_time, session_ip, session_page, session_logged_in) VALUES ('1aac20691c8db95c4efbc3f4b86e0d87', -1, 1398329559, 1398329559, '365385bd', 7, 0)

Line : 170
File : sessions.php