I have a lot of sympathy for posts like this. I used to manage a couple of Seafile installs for clients (and a NextCloud), and they’ve all moved to OneDrive for two primary reasons: 1) no hosting/support costs (the usual reason for anything cloud) and 2) if you have to use Word etc. then you almost get SharePoint/OneDrive for free.
So the only Seafile install I’ve got is the one we use as a tiny 2-man business. One may have seen lots of posts from me as I attempt to migrate a v10 Centos v7 bare-metal system to a new bare-metal system and then, hopefully, onto docker. But to say it’s been a nightmare is an understatement and I’m not quite there yet. I find following the Seafile documentation very difficult, almost the style. Sure, I’m full of cold today so not the best of moods but I’ve been working with computers for 50 years (yes, I’m that old) - installing, updating and migrating Seafile is up there as one of the hardest tasks I’ve ever undertaken.
It’s a shame because for many years our Centos v7 system has worked flawlessly for our needs. I still like the idea of owning our own data and not in the hands of megacorps. Yes, I’m a bit of a conspiracy theorist at time 
It’s interesting that you mentioned Nextcloud because I’ve mentioned before that their documentation just seems to work. Sure, the upgrade system sometimes broke but you could fall back to command line and see exactly what was going on.
Seafile documentation has been discussed before many times. It’s written as a snapshot in time and doesn’t cater for the fact that people might be installing on older versions of Linux
Particular pain points I’ve encountered are:
- The exact list of apt-get modules needed per version and per OS version
- Similarly, and more problematic, the exact list of Python modules needed per version and per OS version. For example, the version of Pillow specified for Seafile 11 throws an error when installed on Debian 13. One Debian 12 the packages throw depreciation errors (yes I appreciate this is why docker is attractive)
- The documentation meanders between separate pages which makes it hard to follow
- Documentation not up to date. For example, Installation - Seafile Admin Manual documents updating v7 to v11 but where is v12?
- Lag in covering new major OS versions not documented, e.g. Debian 13. Okay, so that’s only been out two months but it’ll have been in beta for a long time
- Documentation for extra/updated Python modules often forgets about Python virtual environments: screenshot. Okay so this change (and I fully get why) is outside Seafile’s control but it needs mentioning in documentation - I’ve never sure which user and/or environment I’m in (to be fair, I need to educate myself more on Python venv)
- Configuration nightmare! How many different configuration files?? How many different formats? Once again, I appreciate how you’ve got here - individual components have their own methods. It’s not much better in the Windows world with XML, JSON, text, registry etc
- I don’t really understand how Seafile works at a kind of block level. I’m a programmer at heart so I’m interested in it’s basic architecture
- If I have to type /data/seafile/seafile-server-latest once more, I’ll scream!
- Documentation for migration from older versions to docker is lacking. A migration tool would be wonderful - after all, “all” Seafile consists of is a handful of databases, folders with data files in them
Sorry that was a rant. Must be this cold! But I feel the pain of the original poster. Part of my problem is that I’m not a Linux guru - I’m a lot better than I was and understand much more about how Linux does things. This is a general “issue” with Linux though esp. if you come from the Windows world where you’ve been spoilt by graphical interfaces and seamless (!) upgrades. Want to upgrade Veeam? Run the installer and have a cup of tea…
Now I’ve been an IT manager for many years and I always say “Don’t come to me with a problem without a proposed solution” and I do have some ideas how to improve the above but… is it worth it? This is the tough bit - I get the feeling from the level of discussion here that Seafile usage is reducing esp. if people are decamping to Nextcloud. A sad situation but not unknown.
Is all of this part of the reason? Dunno, I’m not party to Seafile 5 year plan. Could be that they’ve decided they can’t improve documentation, upgrade and migration processes because they haven’t got the resources. I’m mad, I love Mikrotik networking gear - their RouterOS is wonderfully powerful and flexible but I’d have a quieter life if I just stuck to installing Unifi - why? Partly because the documentation and training is lacking. Part of the reason is because Mikrotik isn’t that popular in many parts of the world so general documentation and support is lower.
I’ll stop now… 