The error is caused by an error in the form that's used for the profile.
In the View templates the profile document "wikiprofile" is called, however there is no profile with that name.
I didn't do an upgrade, plain new creation of the database from the template.
I fixed the problem this way:
Create a new action button that opens the profile "Preferences". The profile document doesn't open in a popup now, but who cares?
Changed the values in the Viewtemplate forms to point to the "Preferences" profile in stead of the non-existing "wikiprofile". Now it works.
It may be quick and dirty, but it works now. I must say this template isn't ready for production yet. To many bugs and missing functionality to be a full wiki.
You have however to update this profile document and the Preferences both with the same values