For the record - after upgrading to beta 8, my installation seems to work much better! I can now successfully create and use the addressbook and chat, without errors.
I can also create a notepad that looks normal, but can not add any text to it - the moment I enter text in the input field, I get this error:
Error undefined sending data: Web error: 409 (Conflict) on PATCH of <https://stein.solid.nett.org/public/test6/index.ttl>
This error was there before the upgrade though, so nothing new. I can submit a bug report if it’s not a known problem yet.
But all in all - beta 8 is a good improvement!