Due to the Second EU Payment Services Directive (PSD 2, or Payment Service Directive 2), as of 14 September 2019, all card payments on the Internet must be verified with strong customer authentication.
To meet this requirement, international card organisations have further developed 3-D Secure. 3-D Secure 2.0 will be introduced by Visa and Mastercard in April 2019, and all online merchants in the EU and Switzerland must support it.
Further information to 3-D Secure 2.0 can be found here.
The responsibility for this adjustment lies with the credit card acquirers (e.g. Six Payment Services) and Payment Service Providern (e.g. Datatrans). Hence, there is currently no action needed by the merchants. We are in constant exchange with our credit card partners and will inform you if there is any need for action.
In case you have further question, feel free to write us an e-mail at firstname.lastname@example.org