phpBB : Critical Error

Error creating new session

DEBUG MODE

SQL Error : 1062 Duplicate entry '-1' for key 2

INSERT INTO phpbb2_sessions (session_id, session_user_id, session_start, session_time, session_ip, session_page, session_logged_in, session_admin) VALUES ('3f469c9ed8580d910a046d58fc1460d0', -1, 1548016810, 1548016810, '36e2401e', -6, 0, 0)

Line : 172
File : sessions.php