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 ('49b4b691b7e971fa1bece63b4ea987de', -1, 1398009339, 1398009339, '36cca31a', 7, 0)

Line : 170
File : sessions.php