How to investigate why the event grid delivery failed?

Question

I am trying to use event grid. On the screen below on the event grid subscription details chart I can see that there is a delivery failed event. However, I don't know how I can check the reasons of failure. The subscriber is an azure function, and in the logs I see it wasn't invoked.

How to debug the reasons why the delivery failed in the event grid?

Answer 1

From the documentation:

Event Grid sends an event to the dead-letter location when it has tried all of its retry attempts. If Event Grid receives a 400 (Bad Request) or 413 (Request Entity Too Large) response code, it immediately schedules the event for dead-lettering. These response codes indicate delivery of the event will never succeed.

If the Function is never invoked, I'd suggest checking configuration as EventGrid would retry and you'd see that.