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 ('4c1976f0b29734d8913f30b710f4a055', -1, 1464104236, 1464104236, '36a2b702', -4, 0, 0)

Line : 188
File : sessions.php