For older jailbreaks (iOS 9 and below), iFile works similarly to Filza. Tap the .deb and select "Installer."
This isn’t a manual install error, but if you are trying to re-add a local .deb to Cydia’s source list, the cache is corrupted. Fix: Navigate to /var/lib/apt/lists/ and delete the partial files, then run apt-get update . cydia deb download