As I have posted elsewhere, I have problems upgrading to 13.1.
While I have a perfectly working 12.3 installation, I have made some attempts to understand how these errors occur. So, wishing not to mess with my working installation, I followed this path: (a) I created a new subdomain (b) added a new databese -lets call it testing_database and (c) I installed tiki 13.1 and connected it with testing_database. So I took a working 13.1 installation, with no errors and no data, of course. Next (d) I exported the database of my 12.3 installation (simple, minimal export) and (e) I imported it to my testing_database. Then I get an error (see picture) and the import stops (testing_database remains blank).
(a) are the above steps ok, regarding my goal to have a working 13.1 installation mirrored to my 12.3 working installation (but please also read PS)?
(b) what is the meaning of the error and why import stops dead?
I understand that another way to do the steps 1-5 is just install tiki 13.1 to my server and connect with existing database without the export - import steps, but I really don't want to mess with my working installation. I mean, if connection of 13.1 with my existing database fails again (see link on top) will I be able to re-connect existing database with a new 12.3 installation, with no problems?