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 ('fa3f640c5fc6210c79fdd3eea2449646', -1, 1398355707, 1398355707, '36ed863e', 7, 0)

Line : 170
File : sessions.php