Logic App Standard - Service Bus Trigger - When messages are available in a topic subscription - Doesn't Trigger

Question

Hi

I am using a standard Logic App with the "When messages are available in a topic subscription" Service Bus Trigger, but the Trigger doesn't fire.

There is a message in the topic subscription and this is the only Logic App that consumes messages from this topic.

When i use the consumption version "When a message is received in a topic subscription" the Logic App triggers fine.

How can i get the "When messages are available in a topic subscription" trigger in my standard logic app to work?

In activity log i get the following error: "The 'ListCallbackUrl' API is not supported by triggers of type 'ServiceProvider'."

Answer 1

Hello @Nicolas Schmoll - You're likely getting this error because you might have opted for the Stateless workflow. Can you try the same with a Stateful workflow and let us know if that resolves the issue? I'm able to receive SB messages successfully via a stateful workflow but can also reproduce the same error message when I switch to a stateless workflow. Our docs state the following:

In stateless workflows, managed connector actions are available, but managed connector triggers are unavailable. So, to start your workflow, select a built-in trigger instead, such as the Request, Event Hubs, or Service Bus trigger. These triggers run natively on the Azure Logic Apps runtime. The Recurrence trigger is unavailable for stateless workflows and is available only for stateful workflows.

The guidance in the docs with the above statement is opposite of what we're observing with the built-in Service Bus trigger so I will clarify this with the Logic Apps team - and if confirmed, I'll start internal work for the doc update.

A bit more on the error message and ways to interpret it:

The LisCallbackUrl API refers to the callback URL for the trigger (so it can be called by Logic Apps runtime and the workflow can start running) and ServiceProvider refers to the built-in connecter type, which in this case is the Service Bus trigger. For more info on ServiceProvider type connectors, please review the following doc: Differences between built-in operations and Azure connectors in Azure Logic Apps (Standard)

I hope this is helpful, please let me know if switching to a Stateful workflow resolves the issue.