I got an error "failed to register transaction", what should I do ?

There are many possibilities that you can check regarding this :

1. Please make sure you are using the most updated SDK, please find the updated SDK in our github ↗.
2. Wrong implementation on merchant server, please find more explanation about this in our technical documentation ↗.
3. Network issue. If the problem still exists, please inform log response from your SDK, and send the detail by filling out and submitting this form ↗.

NOTE : this issue can happen only if you integrate with Android.