I sometimes get this with Mullvad in official YouTube app as well.

Oh boy, you haven’t met some Dell Optiplexes.

That shit, for whatever reason, can’t boot from internal DVD drive. I tried with 2 of them. Both had functional drives, I tried disabling secure boot, enabling legacy boot and some other settings which seemed related, but nothing worked. Then for shits and giggles I tried a USB DVD drive and that worked just fine.

I mean, they have a hole in the middle, so if I stack them they let stuff pass.

Meanwhile me with a CD book that has 17 bootable DVDs and CDs plus a separate DVD+RW for more random, less permanent crap and a portable USB DVD drive (the drive is sourced from e-waste and fails to write both DVD+/-RW and CD-RW at 4x, only 2.4x and 10x respectively work).

I like spinny media.

I mean, I also have a Ventoy disk, but I haven’t used it for a looooong time because it’s no fun, but discs are.
I just need a bigger backpack. The WRT54GL is taking up quite some space too.

Much cooler than ventoy, no?

Just a quick guess, did you refresh package lists? sudo apt update

Or if you use the GUI, in top right there is an icon with 3 horizontal lines, under it is option “Refresh the list of packages”.
It seems that should happen automatically though, but it can’t hurt.

If that doesn’t work you could maybe try switching mirrors in software sources, if there is something wrong with these at the moment.

Yes.

Maybe a typo. I usually just hold down shift for shorter acronyms rather than use CapsLock. But sometimes my muscle memory screws up and I press down the shift separate per letter. Probably a habit from phone keyboard (sticky shift key).