
applying auto_increment finally did the job!
I was in the fortunate position to have a similar website (same template, same addons etc) and when I checked the structure of the different tables, I could see which tables had Auto_increment and on which element.
I copied the situation in another phpadmin session on the failing database and I can add pages again!
What a relief!
Klaus: It was a while ago since I exported and imported the database, but I can remember fooling around with the sql compatibility mode.
Thanks to all the respondents
