you already have done an upgrade of the ownCloud code so you can't login in the current state. So why did you do an upgrade if you don't want to actually upgrade?
This is aboslutely wrong. The quoted thread exactly explains how to upgrade and shows detailed steps with an example upgrade path from 8.0.x to 8.2.x. Sure, it doesn't exactly provides each step between 6.x to 8.x but people should be at least able to read simple instructions and apply them to their current environment by replacing some version numbers.
I tried to update because the software offered me this. And after beginning, after making the installation completely unusable, the software tells me, major-version-update is not supported? Then why does it start at all??? Too hard to have one single look into config.php ? The software leaves me alone with a broken installation, where it could have known better.
As stated before: NOW I do not want to update (any more).
Ok, back to my question: Login not possible, you say? Back-draw not possible? From which version do I have to update now? 6.xxx in database and 8.xxx in Code??? And you say, this is explained in the quoted thread, just by replacing some version numbers?
Because you didn't catched up with updates and used such an outdated version like 6.0.4 which was released more then two years ago... Recent oC versions are doing a correct upgrade without showing such an issue.
As the message is telling you, you have done an unsupported upgrade path. For example:
Original version: 8.0.2 Upgraded version: 8.2.6
In this case you have skipped the 8.1.x major upgrade which is unsupported as stated within the documentation.
Remove all files and folders of your oC installation folder except /data/ and /config/
No. It startet, because it did not check pre-requesites at the beginning.
Now I am setting up a fresh 9.1 and new questions come up - thats the reason, why I do not update, if not necessary. For example: My own code does not work any more with 9, which it did with version 6. Never change a running system...
PS: I also still use Win-XP - why? Why not. It works, thats all, I want.
Do you buy a new vacuum cleaner every year? Of course not. But in software business, you expect users to do...
Thread can be closed. No more questions here from me.