In context with customer fields, S/4HANA on-premise has a number of special features compared to the previous ECC 6.0 which must be taken into account.
For example, new DDIC structures were introduced to which the customer fields should be appended in order to be able to use them in Fiori applications. Custom fields must also have unique names.
In the presentation available as a link, which was held by our head of development Andreas Schaller at the SAP Online Track Munich and Vienna 2020, you will find further information:
sotMUCVIE - ABAP Managed Custom Fields.pdf
