If you're seeing this error in Ubuntu 20.04 or similar:

libdvd-pkg: `apt-get check` failed, you may have broken packages. Aborting...

The software you probably installed something that wants to decrypt DVDs. The code for decrypting DVDs is...well, legally complicated, so it can't be packaged, it can only be compiled manually. To jump-start that process, run the following command.

sudo dpkg-reconfigure libdvd-pkg

It should download the source, install it, and BOOM: no more error.