Hi @Pennie
Thank you for your question.
This error code means “transaction declined without any further reason” and it is shown when
the test transaction made by our partner company fails.
You can try saving your credit card directly under www.sbb.ch after loggin in with you personal account: it will be automatically available in the SBB App as well.
If this does not work, please contact your credit card company.
Kind regards
EleonoraS