After upgrading my nop to 2.70, I get an error on the payement plugin I developed (it was working properly through several upgades I've done untile 2.70):

Method 'GetAdditionalHandlingFee' of 'Nop.Plugin.Payments.Keyclient.KeyclientPaymentProcessor' of the assembly 'Nop.Plugin.Payments.Keyclient, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null' doesn't have an implementation.

Any ideas on why it happened with this new nopcommerce version?

Thanks