Support intro
Sorry to hear you’re facing problems. 
The community help forum (help.nextcloud.com) is for home and non-enterprise users. Support is provided by other community members on a best effort / “as available” basis. All of those responding are volunteering their time to help you.
If you’re using Nextcloud in a business/critical setting, paid and SLA-based support services can be accessed via portal.nextcloud.com where Nextcloud engineers can help ensure your business keeps running smoothly.
Getting help
In order to help you as efficiently (and quickly!) as possible, please fill in as much of the below requested information as you can.
Before clicking submit: Please check if your query is already addressed via the following resources:
- Official documentation (searchable and regularly updated)
- How to topics and FAQs
- Forum search
(Utilizing these existing resources is typically faster. It also helps reduce the load on our generous volunteers while elevating the signal to noise ratio of the forums otherwise arising from the same queries being posted repeatedly).
This is no support request but a clarification to the following issue I raised.
The request has been closed but now I see that the proposed solution works fine
after the OS update from bookworm to trixie, but not for subsequent nextcloud updates, e.g. from 32.0.11.1 to 33.0.9.1 in my case. I tried to update to the latest 32.0.15.x version, first.
This update from 32.0.11.1 to 32.0.15.x failed with the message in the subject, i.e.
Access denied for root@localhost (Password NO)
The real solution is to
- set the root password in mysql.user to an empty one or leave it empty
- remove the root password in /root/.my.cnf if existing
After those steps the update to a later version of nextcloud - in my case 33.0.9.1 - works and the backup works fine, too.