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 ('d94d7b5c14c25475f7796d5b7eea0917', -1, 1231533257, 1231533257, '26673f39', 2, 0, 0)

Line : 172
File : sessions.php