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 ('0dc84e7223d914fc52b5ef412f4e4172', -1, 1548017331, 1548017331, '36e2401e', -4, 0, 0)

Line : 172
File : sessions.php