app/updateSession

With this method you can update or read an existing session. The sent data is immediately validated as good as possible, so you can easily show errors in a multi-step-form.
See Session JSON for details.

Update payment session
Use the session hash you got from create and send additional data or override data in your session.

Read payment session
Use the session hash without sending payment-data to read the session.

🚧

The session must not be processed.