I have messed with my Nextcloud installation a while ago and it seems that I broke my webinterface somehow. It isn’t responding properly, e.g. when switching folders.
Desktop and mobile apps work fine so I let it slide for a while.
As I’m still on v18 I’d like to use the upgrade to start from scratch, however, keep all my data of course.
Is there a best-practice guide on how to exchange the underlying Nextcloud server installation but keep all the data (and, if possible, even all the config data)?