On 12/09/19, netbank adapted its online banking to the new Payment Services Directive (PSD2): https://www.netbank.de/privatkunden/service/Starke-Kundenauthentifizierung/#.
Currently, there can occur errors when doing payments. If you receive an error message, please check in your banks' online banking portal if the payment was completed.
Thank you very much for you understanding.
You can find detailed information about PSD2 in our blogpost.