In the patron import tool, the Notes area includes this comment: 'The fields 'branchcode' and 'categorycode' are required and must match valid entries in your database.' I didn't include surname in an upload, and received this error: "Line 2 Critical field "surname" missing", but that field isn't listed in the Notes area. Should the surname also be listed in the notes area as a required field be or is this a bug and the surname shouldn't be required in an upload? I wondered if the patron import tool might be also be using the fields in our BorrowerMandatoryField sys pref, which includes the dateofbirth|surname|cardnumber|firstname fields, but in the next upload test, I only included branchcode, categorycode, cardnumber, and surname fields in the upload, and the file uploaded successfully.
I can't reproduce this problem in more recent versions of Koha. Since there is no maintainer for 3.18.x I think that means this should be considered resolved.