Okay, so in having a 2.5 year old github report closed off saying “CentOS not supported”, what distros are? This is what I hate about Linux. You put your eggs in a basket to only found out that particular flavour isn’t supported anymore. I’m aware of the problems with IBM/Redhat and recent changes although the details goes over my head. So I’m guessing that the only basket to consider maybe is some Debian based distro like Ubuntu. Rocky Linux have said they can carry on the RHEL direction but I’m wary.
I’m in the middle of a nightmare with Nextcloud with a client. Seafile is a model in stability in comparison. I love the idea of 3rd party cloud storage but I feel I’d have a happier life in the clutches of Microsoft and OneDrive/SharePoint. Can’t believe I’ve just written that! 
PS. If CentOS isn’t supported anymore, why are there still CentOS releases (11.0.4) and CentOS instructions still on recent documentation?
CentOS is mentioned in the Release Info for Seafile Pro 10 and older but not for Seafile Pro 11 and higher.
We now officially only support Docker based method (preferred) and Ubuntu. For CentOS, we still upload the binary packages for some customers that not willing to change. But it is likely to be dropped when all the customers using CentOS switching to Docker based deployment.
It’s not specifically about not been willing to change but time and money. I looked at the migration process and shuddered. Especially as these instructions don’t seem to cover Seafile running in docker on another server:
Data migration - Seafile Admin Manual
I don’t understand what you mean by linking this document. This document is about migrate data between different storage backends (S3 storage and local disk).
If you want to migrate from non-docker deployment to docker deployment, it is this document: Migrate from non-docker deployment - Seafile Admin Manual
When we talk about documentation being key, it’s examples like this. I found that page by searching for Seafile migration. It talks about migration between backends. I consider moving from one host to another a change of backends. Also, cross reference the articles more - a link at the top to the page you linked would be ideal.
But once again confusing messaging:
Starting from 9.0, binary packages cannot run on CentOS 7, CentOS 8. If you need to run Seafile on CentOS or some other platforms that are not supported by binary packages,
If it’s not supported, stop doing releases for it. Version 9 is 3 major releases ago.
