Are you updating from the legacy Azure Service Bus transport? If so, the API is quite a bit different. The “UseForwardingTopology” method doesn’t exist; forwarding topology is the default. Also the topology is handled differently than it was in the legacy transport and the API for it was only introduced in v3 of the new transport. We have some information on how to use it here but keep in mind the differences between v2 and v3 of the transport. You can view the documentation for each version by selecting the correct version in the article header.