Azure Service Bus Failed to Receive error

I’m setting up a test app as my first use of NServiceBus (v9) with Azure Service Bus. It’s running as a Linux container on Azure Container Apps. The test app publishes a test event to a topic, and has a handler to consume the event which is just supposed to log a success message.

Publishing to the topic is working, but receiving is not and I’m getting the following error:

WARN Failed to receive a message on pump ‘Processor-Main-MyNamespace-1572b765-c93a-48c9-985b-2248d4bb7673’ listening on ‘MyNamespace’ connected to ‘’ due to ‘Receive’.

Exception: Azure.Messaging.ServiceBus.ServiceBusException: The messaging entity ‘asb-xxx:Topic:my-topic-name|amqps://;9:14:59:source(address:/MyNamespace,filter:)’ could not be found.

The container app is configured to use a user-assigned identity, and that identity is in the Azure Service Bus Data Owner role.

The topic and the subscription do exist, so I’m not sure what messaging entity it’s not finding. It could perhaps be the address:/MyNamespace part as I’m not yet sure what that relates to.

Changing the endpoint name has fixed the issue. It was the same as my code namespace and differed only in case from my topic name. My guess is that the endpoint name must not be a case-insensitive duplicate of a topic name.

Hi @rick,

Thanks for sharing this. We will look into it.
I have raised this separately in this issue.
Feel free to subscribe if you want to track progress.

Something interesting to read could be this documentation that describes the topology.

Hi Rick,

There are a few documents that you might find helpful specifically related to Azure Service Bus.

This one describes how the topology is implemented and why. By default, there is a single topic topology.

Also, there is some general guidance for working with the Particular Software Platform in Azure

If you encounter any further problems, feel free to contact us here or by opening a non-critical support case.