Hi Teitbite,
After the reply that I wrote yesterday, I updated the extensions that were causing the other error messages. Then I disabled the error reporting on this develop site.
Editing the item that I referred to, still gives an error, on the bottom of the page. It looks a bit different now, as the reference to the php file is omitted. Yet it is essentially the same error:
Cannot use object of type ContactenhancedViewEdit as array
I've added screen shots of the top and the bottom of the page (it's rather long and the part in the middle does not contain any error messages).
It seems to me that updating the other extensions, though certainly important, does not help to solve this particular issue. And, as I wrote earlier, switching to the Protostar template did and still does solve the issue.
So I would like to ask you if you could still investigate this problem. There seems to be a type mismatch in line 13 of params.php, presumably with the variable displayData (on which a method getForm() is being applied).
Kind regards, Frits