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 ('a1bc8bfceba1f32f6efb9477dcb89240', -1, 1406608517, 1406608517, '365231c8', 7, 0)

Line : 170
File : sessions.php