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 ('b184914436e0f2d9e3ac9479e41937db', -1, 1398398089, 1398398089, '36cc67b3', 7, 0)

Line : 170
File : sessions.php