How to recover an app service

Many apps ship a systemd unit (examples from inventory: vaultwarden, ntfy, jupyterlab, searxng, code-server, glances, httpsh).

systemctl status vaultwarden --no-pager
journalctl -u vaultwarden -n 50 --no-pager
sudo systemctl restart vaultwarden
yunohost app info vaultwarden
curl -sI https://exchange.neuralmeadow.xyz | head -8

Replace unit/domain for the affected app (apps table).