Unable to connect to indexer.
Your jackett service have crashed. This have started happening to me as well few times a week, and is still happening from 0.8.x untill 0.9.x as i know. i am trying 0.10 atm.
easiest solution is to reinstall jackett
https://github.com/Jackett/Jackett/releases/
then run test on all your indexers again
Even if that might be a temporary soloution you have to do now and then :/
also somone mentioned that changing API to 2.0 whould be a good idea.
--> /api/V2.0/indexers/all/results/torznab/
Yeah there is! Jackett is preinstalled plugin and comes with qbittorrent but you also need to install Jackett Windows service to add torrent indexers. When I clicked check for updates, It gives me all build-in plugins including Jackett. So Jackett is always pre-installed with a few more other plugins. If nothing comes when you clicked to check for updates, you should try to reinstall qbittorrent. You can get Jackett Windows service/gui from there https://github.com/Jackett/Jackett. https://github.com/qbittorrent/search-plugins/wiki/How-to-configure-Jackett-plugin this is a Jackett configuration for qbittorrent. These two links will do the trick.It is explained in detail.All you need is just follow the guide.