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) VALUES ('4907f5c72962e0a77c7171ee1f5982b1', -1, 1409151243, 1409151243, '36508d9c', 10, 0)

Line : 315
File : sessions.php