Your main problem is your distro is EOL (end of life) as of July 2020 :
https://wiki.ubuntu.com/EoanErmine/ReleaseNotes
Support lifespan
Ubuntu 19.10 will be supported for 9 months until July 2020. If you need Long Term Support, it is recommended you use Ubuntu 18.04 LTS instead.
(i.e. eoan ermine = Ubuntu 19.10)
I think they give a 3 month grace period after official EOL before they take the repos offline…
I can’t help you because I’ve NEVER tried to run an EOL Ubuntu… I’ve always either updated it to the next release before it went EOL - or - more commonly just wiped it and done a fresh install (I don’t have to worry too much about backups because my “data” is sync’d via personal cloud).
These days? I NEVER run anything but an LTS release… i.e. 20.04 (and previously 18.04)…
I think there are ways / methods of editing your apt files to point to the few remaining sources that host archived versions of old release updates - I can only suggest you do some searching for how to do that… Sorry - I can’t really be of help…
But there’s this here :
and here :
https://help.ubuntu.com/community/EOLUpgrades
and this :
## EOL upgrade sources.list
# Required
deb http://old-releases.ubuntu.com/ubuntu/ CODENAME main restricted universe multiverse
deb http://old-releases.ubuntu.com/ubuntu/ CODENAME-updates main restricted universe multiverse
deb http://old-releases.ubuntu.com/ubuntu/ CODENAME-security main restricted universe multiverse
# Optional
#deb http://old-releases.ubuntu.com/ubuntu/ CODENAME-backports main restricted universe multiverse
Where in your case - you’d replace “CODENAME” with “eoan”.
I’ve also no idea if you can still “do-release-upgrade” on an EOL release.
– edit update / post script –
Something like this might work for you also :
Become root :
sudo -i
Make a backup :
cp /etc/apt/sources.list /etc/apt/sources.list.20210615
Make the changes in place :
sed -i 's/ie.archive/old-releases/g' /etc/apt/sources.list
And pray to whatever deity is your preferred choice that you didn’t add any PPA’s 