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 ('4ec37f7bda96f5f80c0e2181806a645b', -1, 1217005347, 1217005347, '26673f12', 28, 0, 0)

Line : 172
File : sessions.php