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 ('ca97b8f14cbf5c1b4ef37db167787d74', -1, 1438748206, 1438748206, '36c4eed2', -4, 0, 0)

Line : 189
File : sessions.php