Please note that the data within all JSON objects is encoded using UTF-8 and then must be also Base64 encoded. This applies in particular to special characters such as "Umlaute" and diactrics.
Paygate validates JSON objects on all requests which contain parameter "MsgVer=2.0". This is independently of the fact whether 3DSecure2 is activated for your MerchantID.
Please make sure no empty parameters or objects are submitted. Under such circumstandes Paygate assumes an error and rejects the transaction.
- Basics of Base64-encoding