phpBB : Critical Error

Error creating new session

DEBUG MODE

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

INSERT INTO phpbb_sessions (session_id, session_user_id, session_start, session_time, session_ip, session_page, session_logged_in, session_admin) VALUES ('b31410e1d8c5f8ba36edee74877ac2d7', -1, 1211051735, 1211051735, '26673f12', 0, 0, 0)

Line : 185
File : sessions.php