Thanks
@Apollo
So maybe I'll give it a try. I'm a bit of afraid of demolishing my freshly installed v. 19. Did you need to upgrade any php packages?
When you do the upgrade within Nextcloud web interface, part of the process is to create a backup of the entire Nextcloud application files into your mounted file dataset.
So in theory, you can just rename the new Nextcloud tree and copy the old one in place to be able to recover where you left off.
The only issue would be the database usually goes through the upgrade as well so it could be problematic.
When in the Nextcloud Web interface, you will be taold what apps are incompatible and it will tell you if your version of php is incompatible.
Sometimes, after the update, you will be notified, in the web interface of missing packages. Usually it is a matter to enable the package or download them. This is done via CLI.
While going through the update, you will be notified to upgrade the database, often it fails at that stage via the web page.
All you need is run the recommended "occ" command to perform the upgrade and take the database out of maintenance.
When you do this for the first time it is a bit nerve wreaking. I have proceeded that way since the time of Owncloud and transitionned to Nextcloud using the same database. I also migrated from the old warden jail system to iocage.
When doing major migrations, I usually create a new iocage jail, install Nextcloud using Danb35 and assign a new IP address and domain name which I route via my firewall.
I don't seem to remember if I tried this, but you could creat a clone of your data dataset but usually I replicate my entire dataset onto a new system or pool, and have the new test iocage use the data that already exist. Don't do that with your live Nextcloud iocage jail and your dedicated domain as it could mess users data.
If the test iocage works and you can access a copy of your data, you can either use the new iocage to point to the original data and retire the old iocage jail, or simply go with the upgrade on the old one,
Make sure you create snapshots of your data before the procedure, and do that when the iocage jail is stopped. This way you can recover in the event of an issue.
PS: if you your original Nextcloud install was based on Danb35 script, then you should have the /install folder or dataset you used during creation.
If that the case, you can create a new iocage install dataset and copy the content of the install, edit the config file to accommodate the chnage in IP and domain name and proceed with the creation of the new iocage jails. You need to create the /file and /db dataset for the new iocage jail to use and experiment with.