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 ('6f9b1899b81a544fd9e02ea8413ffcd3', -1, 1246727304, 1246727304, '26673f39', 0, 0, 0)

Line : 189
File : sessions.php