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 ('85ce66ebd784512398069ff778682a7f', -1, 1280443285, 1280443285, '266bbf50', 3, 0, 0)

Line : 187
File : sessions.php