On Tue, 24 Nov 2015 07:52:47 -0500, Stephen Gallagher wrote: > I've upgraded several family members directly from Fedora 21 to Fedora 23 > in the last week with no issues whatsoever (of course, I also curate > their repository selection, so they don't end up with incompatible > packages).
Aye, there's the rub. It is not just update from an "original" installation of N-2 to N, it is update from N-2 plus whatever additional repository packages were installed plus additional non-repository software and user configuration that you want to upgrade. The starting condition is quite variable, and may include old versions of applications because these are familiar to the user or incompatible with more up-to-date software. When system-upgrade fails (if you are lucky, this will be obvious; if unlucky, it may not be recognized until after the event), the only way back to the starting condition is a full system restore. Many users will back up their own data, and, if upgrade ends badly, plan to recover with a new installation (of N, N-1, or N-2) and necessary software, followed by restoration of their personal data. This is the most reliable upgrade strategy: no exposure to problems with old stuff, and it defines how to get from a well-known initial state to the user's working environment. In this case it may be impossible to fix an upgrade problem, because there is no way to reconstruct the original state and verify successful upgrade is possible. Of course, these considerations also apply to the single-release upgrade. The situation just gets worse the farther back one goes. And sometimes there simply is no upgrade path: the new software is just incompatible with the old. To use the new system, you must adapt to it. (Remember the agony voiced by some GNOME2 users when GNOME3 came along?) Unlike new installation with its well-defined result, system-upgrade (with dependencies on user configuration and possibly incompatible pieces of software) necessarily has some vague result. It is undeniably valuable and extremely convenient, but unavoidably a second-class facility. We may insist system-upgrade of a newly installed N-1 to N works, and further insist system-upgrade of a newly installed N-2 to N works, but this is deceptive. Once a user configures and uses his system, system-upgrade is unpredictable. To add my own to Mr. Gallagher's anecdote, my single attempt at "dnf system-upgrade" from 21 to 23 failed. After upgrade, my userid was not displayed on the login screen. Login in text mode was possible. After an hour or two tinkering with gdm configuration, I gave up, did a new install of 23, and configured it without difficulty. Several times I have used "dnf system-upgrade" from 22 to 23 without problems. Conclusion: release-skipping upgrade is more difficult than single-release upgrade (and probably not worth the effort to fix.) If anyone would like to investigate the problem I experienced, I am willing to install a new 21 system and see if I can reproduce the error. -- test mailing list test@lists.fedoraproject.org To unsubscribe: http://lists.fedoraproject.org/admin/lists/test@lists.fedoraproject.org
