When several cataloguers are cataloguing simultaneously and the autoBarcode system preference is set to generate the barcodes in 1, 2, 3 form, it is possible that the same item barcode will be assigned to two different items at the same time which prevents the record from being saved. Koha should lock the barcode in some way once it has been allocated, even if the item record is not yet saved.
What if... Koha locked the barcode on cataloguing instead, and the barcode got calculated on saving?
(In reply to Tomás Cohen Arazi from comment #1) > What if... Koha locked the barcode on cataloguing instead, and the barcode > got calculated on saving? I think this would work and avoid some of the known issues. We also do it for cardnumbers, so why not for barcodes :)