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Mise à niveau du système avec la commande dnf system-upgrade

Qu'est-ce que la mise à niveau du système avec la commande dnf-system-upgrade ?

dnf-plugin-system-upgrade est un greffon du gestionnaire de paquets dnf qui prend en charge les mises à niveau du système. C'est la méthode de mise à niveau recommandée depuis Fedora 21.

Que fait la commande dnf system-upgrade ?

La commande dnf system-upgrade permet de passer votre système sur une nouvelle version de Fedora, en utilisant un mécanisme similaire à celui utilisé pour la mise à jour de paquets hors ligne. Les paquets à jour sont téléchargés alors que le système continue à fonctionner normalement, puis le système redémarre dans un environnement particulier (mis en œuvre en tant que cible systemd) pour les installer. Une fois l'installation terminée, le système redémarre à nouveau sur la nouvelle version de Fedora.

Comment l'utiliser ?

  1. Faites une sauvegarde de vos données importantes. Tout changement sur le système est potentiellement à risques ; préparez-vous à toute éventualité ! Dans le cas où vous mettez votre station de travail à niveau, il est aussi recommandé de téléchager une Image live de Fedora Workstation et de vous assurer que votre matériel (cartes graphiques, cartes wifi, etc.) fonctionne correctement avec le dernier noyau et les derniers pilotes.
  2. Mettez votre système à jour en utilisant le système de mise à jour standard pour votre ordinateur ou dnf:
    # dnf upgrade --refresh

    Il est recommandé de redémarrer votre ordinateur ; en particulier sir vous venez d'installer un nouveau noyau.

    • Veuillez noter qu'il y a un problème lorsque vous utilisez un thème de démarrage qui n'est pas le thème plymouth par défaut. Si c'est votre cas, lisez la description du problème pour savoir s'il n'affectera pas votre mise à niveau.
    • Vérifiez attentivement votre configuration de DNF dans le fichier /etc/dnf/dnf.conf. Si vous avez effectué des personnalisations (qu'elles soient manuelles ou par l'intermédiaire de tierces parties), il est recommandé de revenir à la configuration par défaut avant de mettre votre système à jour et à niveau.
  3. Installez le paquet Package-x-generic-16.pngdnf-plugin-system-upgrade :
    # dnf install dnf-plugin-system-upgrade
  4. Téléchargez les paquets à jour :
    # dnf system-upgrade download --refresh --releasever=33

    Modifiez le numéro de version --releasever= si vous désirez effectuer une mise à niveau vers une version différente. La plupart de gens désire mettre leur système au niveau de la dernière version stable, qui est 33, mais si vous utilisez actuellement Fedora 31, il se peut que vous vouliez mettre votre système au niveau de Fedora 32. Vous pouvez aussi utiliser 34 pour une mise à niveau vers Branched ou rawhide pour une mise à niveau vers Rawhide (attention : ces versions ne sont pas stables).

    • If some of your packages have unsatisfied dependencies, the upgrade will refuse to continue until you run it again with an extra --allowerasing option. This often happens with packages installed from third-party repositories for which an updated repositories hasn't been yet published. Please study very careful the output and examine which packages are going to be removed. None of them should be essential for system functionality, but some of them might be important for your productivity.
    • In case of unsatisfied dependencies, you can sometimes see more details if you add --best option to the command line.
  5. Trigger the upgrade process:
     $ sudo dnf system-upgrade reboot

    This will reboot your machine immediately. The system should boot again into Fedora using the same kernel, but this time, the upgrade process appears on the boot screen.

  6. Wait for the upgrade process to complete.

Frequently Asked Questions

How do I report issues that I find with upgrades?

First see Common F33 bugs or Common F34 bugs to check if the problem is a very prominent issue we already know of. If it is not there, search for an existing bug report. If you do not see a report that matches your symptoms, you can file a new report from the search page. Please follow the bug reporting instructions mentioned in this README and in man dnf.plugin.system-upgrade.

If you hit issues after upgrade with a specific package, file a bug against the package with which you are having issues.

Does DNF system upgrade verify the software it runs or installs during upgrade?

Yes. The package signing keys for newer Fedora releases are sent to older Fedora releases in order to allow DNF to verify the integrity of the packages it downloads. You can disable this function with the --nogpgcheck parameter if you need to do so for any reason (not recommended, you're then opened to attacks from malicious software).

Will packages in third party repositories be upgraded?

Yes, if they are set up like regular DNF repositories and do not hard code the repository path. Commonly-used third party repositories usually work fine, but if you attempt to upgrade prior to or soon after an official Fedora release, they may not have updated their repository paths yet, and DNF may be unable to find their packages. This will usually not prevent the upgrade running successfully, though, and you can update the packages from the third-party repository later.

Can I upgrade from an End of life release?

Note that Fedora strongly recommends against ever running an end-of-life release on any production system, or any system connected to the public internet, in any circumstances. You should never allow a production Fedora deployment to reach end-of-life in the first place.

With that in mind, if you do have an end-of-life release newer than Fedora 20 installed on a system you cannot just discard or re-deploy, you can attempt to upgrade it, though this is a less-tested and less-supported operation. You can try to upgrade through intermediate releases until you reach a currently-supported release, or try to upgrade to a currently-supported release in a single operation. It is not possible to state with certainty which approach is more likely to be successful.

If you attempt to upgrade across more than two releases in one operation, please also read the next answer.

If you have Fedora 20 or earlier installed, you cannot upgrade with DNF system upgrade alone. You must upgrade at least part of the way using bare dnf or yum. You can either upgrade to Fedora 21 that way and then upgrade the rest of the way using DNF system upgrade, or you can attempt the entire upgrade using bare dnf or yum. Note this method is in itself not an officially recommended upgrade mechanism. To be frank, any upgrade from Fedora 20 or earlier is very much done 'at your own risk'.

How many releases can I upgrade across at once?

The most common scenario is an upgrade across just one release (e.g. Fedora 32 to Fedora 33). However, for the first month or so after a new release comes out, upgrades from the last-but-one release to that release are 'supported', in the sense that we include this scenario in the Fedora Release Criteria, test it for at least clean installs of supported package sets, and will treat bugs discovered in such upgrades as significant. The Fedora Release Life Cycle is specifically designed to provide this approximate one month 'grace period' so you can choose to upgrade long-lived systems only once every two releases, rather than having to do it every release.

Around a month after the new release comes out, the last-but-one release goes End of life, at which point the previous question applies. Still, that upgrade is still pretty likely to work successfully for some time after the release goes end-of-life.

Upgrades across more than two releases are not 'supported', and issues encountered in such upgrades may not be considered significant bugs. Note that any upgrade across more than two releases must by definition be an upgrade from an end-of-life release, and so the previous question applies here too.

When upgrading across multiple releases, you may find you need to import the target release package signing key manually. Fedora releases usually only have the package signing keys for the next two releases installed (because they go end-of-life before the N+3 release is branched). Before Fedora 22, it was not consistently the case that every release had keys for the next two releases, either. If dnf complains about a missing key, this is what you must do.

Can I use DNF system upgrade to upgrade to a pre-release (e.g. a Beta)?

Yes. It should always be possible to attempt such an upgrade. Of course, this function is as subject to temporary breakage as is any other aspect of a pre-release, and generally speaking, the earlier the release in question, the less likely it is to work without problems.

Optional post-upgrade tasks

These are tasks you can do after a successful upgrade. They are mostly intended for power users. If you are a general user who doesn't use terminal daily, you don't need to worry about this.

Update system configuration files

Most configuration files are stored in /etc. If there are any updates to them and you touched some of those files before, RPM creates new files with either .rpmnew suffix (the new default config file), or .rpmsave suffix (your old config file backed up). You can search for these files, go through the changes and make sure your custom changes are still included and the new defaults are applied as well. A tool that tried to simplify this is rpmconf. Install the package, and then use it as:

$ sudo rpmconf -a

See more information in its manual page.

Clean up old packages

You can see list of packages with broken dependencies like this:

$ sudo dnf repoquery --unsatisfied

Ideally there should be none. If there are some, consider removing them, because they are not likely to work properly anyway.

You can see duplicated packages (packages with multiple versions installed) like this:

$ sudo dnf repoquery --duplicated

For ordinary packages, just the latest version should be installed. But there can be exceptions to the rule, only remove what you are sure you no longer need.

Some packages might stay on your system while they have been removed from the repositories. See them using:

$ sudo dnf list extras

If you don't use these, you can consider removing them. Please note that this list is only valid if you have a fully updated system. Otherwise you'll see all installed packages which are no longer in the repositories, because there is a newer update available. So before acting on these, make sure you have run sudo dnf update and generate the list of extra packages again. Also, this list might contain packages installed from third-party repositories for which an updated repository hasn't been published yet. This often involves e.g. RPM Fusion or Dropbox.

You can remove no-longer-needed packages using:

$ sudo dnf autoremove

but beware that dnf decides that a package is no longer needed if you haven't explicitly asked to install it and nothing else requires it. That doesn't mean that package is not useful or that you don't use it. Only remove what you are certain you don't need. There's a known bug in PackageKit which doesn't mark packages as user-installed, see bug 1259865. If you use PackageKit (or GNOME Software, Apper, etc) for installation, this output might list even important apps and system packages, so beware.

Resolving post-upgrade issues

Only follow up these steps if you have troubles with your upgraded system. It should not be needed in the vast majority of upgrades.

Rebuilding RPM database

If you see warnings when working with RPM/DNF tools, your database might have gotten corrupted for some reason. It is possible to rebuild it and see if resolves your issues. Always back up /var/lib/rpm/ first. To rebuild the database, run:

$ sudo rpm --rebuilddb

Using distro-sync to resolve dependency issues

The system upgrade tool uses distro-sync method by default. If your system stayed partly unupgraded or you see some package dependency issues, you might try to fix it by running another distro-sync manually. This tries to make your installed packages exactly the same version as in currently enabled repositories, even if it meant downgrading some packages:

$ sudo dnf distro-sync

A stronger variant also allows to remove package for which package dependencies can't be satisfied. Always carefully review which packages are going to be removed before confirming this:

$ sudo dnf distro-sync --allowerasing

Relabel files with latest SELinux policy

If you see warnings that some actions were not allowed because of current SELinux policy, it might be a case of having some files incorrectly label with SELinux permissions. This might happen in case of some bug or if you had SELinux disabled in some point of time in the past. You can relabel the whole system by running:

$ sudo touch /.autorelabel

and rebooting. The next boot will take a long time and will check and fix all SELinux labels on all your files.