Hello. I have the same problem on my whmcs 8.13.1.
Client orderd server upgrade. Payments done for upgrade. The module updated to a different tariff, but the letter to the customer did not arrive.
Hello. who know how fix this error? i use GoCardless payment module.
One of your parameters was incorrectly typed - scheme "sepa" is not a valid value. Must be one of [ach, autogiro, bacs, becs, becs_nz, betalingsservice, pad, sepa_core, ].