Hi Katrin
hard to debug remote... next things I'd check is probably the System information tab on the about page and emptying out the BorrowerMandatoryField and BorrowerUnwantedField system preferences to see if anything there makes a difference.
Thanks for the hints... The Koha menu "About Koha > System information" shows "No warnings". The Koha system preference "BorrowerUnwantedField" is empty. The Koha system preference "BorrowerMandatoryField" only contained "surname". I removed that and tried again to save a new patron, but it made no difference and didn't work. Best wishes: Michael -- Geschäftsführer · Diplombibliothekar BBS, Informatiker eidg. Fachausweis Admin Kuhn GmbH · Pappelstrasse 20 · 4123 Allschwil · Schweiz T 0041 (0)61 261 55 61 · E mik@adminkuhn.ch · W www.adminkuhn.ch