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 ('a15033f7f7efe4f2aad33ef1b2bf39e1', -1, 1397901962, 1397901962, '36c624b3', -9, 0)

Line : 158
File : sessions.php