If you are trying to unblock someone on Instagram and keep seeing the "User Not Found" message, it usually happens because you cannot access their profile page directly to hit the unblock button. This error often occurs if they have also blocked you (a "mutual block"), changed their username, or deactivated their account.
It can be incredibly confusing when you try to unblock someone on Instagram, only to be met with the dreaded error. how to unblock in instagram user not found