Thatās a strange message. Iāve upgraded many sites from 8.5.x to 8.5.9 without any issues, can you share a screenshot of this message? Are you trying to upgrade through the dashboard or are you manually upgrading?
Iāve never upgraded via the dashboard, I always do the manual upgrade. As long as you do a database backup and backup your application/config directory I would push the button, I have not had any issues with this upgrade so far. The only thing I can see that might happen is doing it from the dashboard it might time out.
Here is the documentation for manually upgrading if you want to try that instead (I would still do a database and application/config backup) - How to Upgrade Concrete CMS I use the āUpgrading via the command line (Version 8 and above)ā method
Yes, the timeout is a real problem. Your right. The CMS runs on a simple webhosting system with limited resources. So it is better to run it from commandline. Thank you for the link. I will read it and try it. I have a backup from database and the whole web-root. So I assume I m save
Iām glad the 8.5.9 upgrade worked well. Technically the upgrade to 9.1.2 should work the same way, but if you have any packages or themes that are not v9 ready you could run into some major issues. If you are able I would try that one in a development environment.