Shrinking Harddisk On Proxmox For Nextcloud. HOWTO Make Sure, Nextcloud Will Run After Shrinking?

Hi everyone,

I am using Nextcloud on a proxmox-server and all runs fine. But as I realized, the harddisk I created was too big for my needs. I want to shrink it from 200 GB to 100 GB, which will be enough for my needs.

I found how to shrink a virtual (qcow) harddisk in proxmox, it is well described on several websites, and of course I already tried. Everything went well, the harrdisk was only 100 GB, the system started without any errors, but - Nextcloud could not be reached - I got a server error.

So it seems like there has to be done much more, than shrinking the virtual harddrive and to tell proxmox, that the harddrive is 100 GB now.

My virtual harddisk is not encrypted, my Nextcloud-Version is 21.04.

Here is my question: what has to be done to Nextcloud before (or after) shrinking the virtual harddisk?

Thanks so much,