Which Ubuntu or Debian version to install Koha on

Use the current Ubuntu LTS or the current Debian stable, 64-bit, and nothing else. Both are what the Koha community builds and tests packages against, and both give you years before the question comes up again. Before you install anything else on the server, confirm it in one command: apt-cache policy koha-common must show a candidate version.

This takes two minutes on a fresh machine and saves rebuilding one. Add the repository, then ask apt whether a package exists for this release:

$ wget -qO- https://debian.koha-community.org/koha/gpg.asc \    | sudo gpg --dearmor -o /usr/share/keyrings/koha-keyring.gpg$ echo "deb [signed-by=/usr/share/keyrings/koha-keyring.gpg] \https://debian.koha-community.org/koha stable main" \    | sudo tee /etc/apt/sources.list.d/koha.list$ sudo apt update$ apt-cache policy koha-common

A candidate version and a version table means this release works. Candidate: (none), or an install that then reports unmet dependencies, means it does not — and the fixes for each are in apt cannot install koha-common.

Koha is a large Perl application, and the packaged install deliberately does not bundle its own Perl libraries. koha-common depends on your distribution's packages for them — dozens of them. That is the right decision for a server you have to keep patched for a decade: security updates for those libraries arrive through the same apt upgrade as everything else, instead of sitting frozen inside an application directory.

The price is that Koha can only be installed where the distribution happens to ship versions new enough for the release you are installing. That is not a policy the project chooses release by release; it is arithmetic, and it is why "supported" moves.

The second half of the answer is the koha-* commands. koha-create, koha-dump, koha-plack, koha-rebuild-zebra and the rest are Debian packaging, not part of Koha's Perl. They assume the Debian layout — instances under /etc/koha/sites/, logs under /var/log/koha/, Apache configured with a2ensite, services under systemd. On a distribution without the packages none of those exist, so every answer you find in the manual, on the mailing list or here has to be translated before it can be used. That, far more than getting Koha running once, is what makes a non-Debian install expensive.

Before the catalog goes live, rebuild. It is an afternoon, and every later problem gets easier.

Once it is live, do not upgrade the distribution underneath a running Koha in place. Build the new server beside it, restore a dump onto it, test it properly, and move the DNS — the same procedure as any migration, and the only one where a failure leaves the old catalog still working.

If the choice you are really weighing is packages against a source install rather than one distribution against another, that decision has its own consequences — and they last longer.