On 04/03/2021, at 17:24, Tim Shaw wrote:

The database migration from 10 to 12 has been sitting without any obvious progress for over an hour - is it stuck?

Do you have Ubuntu or Debian channels synced?

If yes:

https://www.uyuni-project.org/doc/2021.02/release-notes-uyuni-server.html#_fix_version_comparison_algorithm_for_deb_packages_ubuntu