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 ('6a78a82ccd3793c291c1aaa343cf0074', -1, 1506196885, 1506196885, '36e09ee8', 2, 0, 0)

Line : 187
File : sessions.php