Why do I have occasional Jackett errors with Qbittorrrent
I've been seeing those intermittent Jackett errors too for at least 3 years now in qbittorrent.
Seems to be some kind of time-out issue were the Jackett server takes too long to respond to a search request.
(Or delivers the first part of the response and then takes too long to provide subsequent parts.)
There is nothing you can do about this, besides configuring qBittorrent no to use Jackett anymore.