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 ('cc61cac12ad8f838f046b6bd61b17d69', -1, 1438539553, 1438539553, '36e30d22', -1, 0)

Line : 158
File : sessions.php