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 ('88d4fa4460bbee21b8c0f769e5242f92', -1, 1410910013, 1410910013, '36575d01', 1, 0, 0)

Line : 172
File : sessions.php