topic Re: Deserialization error when publishing events to Eventstream via Event Grid after initial success in Eventstream

Deserialization error when publishing events to Eventstream via Event Grid after initial success

AditiPattnaik — Thu, 30 Apr 2026 06:41:59 GMT

Hi,

I’m trying to ingest events into Microsoft Fabric Eventstream using Azure Event Grid and ran into an issue that I’m unable to understand.

Here’s what I did step by step:

I created an Event Grid Namespace, followed by a custom Topic.
In Fabric Eventstream, I configured a Custom Source by selecting the Event Grid namespace and topic.
From the Azure portal, I noted down the topic endpoint and access key.
Using Azure Cloud Shell, I started publishing events to the Event Grid topic.

Initially, my plan was to ingest 10 events at once, but that didn’t work. So I changed the approach and started publishing the events one by one.
This is where the issue started, the first two events were published and consumed by Eventstream successfully.When I tried to publish the third event, Eventstream threw a deserialization error.Despite that, only the third event (and subsequent ones) fail with a deserialization issue. What’s confusing is that the schema is exactly the same for all events and I followed the same steps, used the same format, and didn’t change anything between events.

Has anyone faced a similar issue when publishing events from Event Grid to Fabric Eventstream?
What could cause deserialization? Any known limitations or best practices for publishing events via Event Grid to Eventstream?

Thank You

Re: Deserialization error when publishing events to Eventstream via Event Grid after initial success

svelde — Wed, 06 May 2026 19:30:01 GMT

Hello AditiPattnaik ,

welcome and thank you for your question at the Fabric Community forum.

I see you try to ingest JSON messages in Fabric having an Eventgrid Namespace as source.

Note that you are probably using this source, useful for routing your CloudEvents or MQTT (IoT) messages from Azure Event Grid Namespace to Fabric:

I expect you have configured your Eventgrid Namespace as an MQTT broker already?

It's a bit confusing that you use curl instead of an MQTT client like MQTTX or MQTT Explorer. This I have used several times already.

Can you try this again with an MQTT client as seen in this blog post?

If this answer helps you, a thumbs-up or marking it as accepted answer is appreaciated. All community members with similar questions will benefit by doing so. Your contribution is highly appreciated.

Re: Deserialization error when publishing events to Eventstream via Event Grid after initial success

v-aatheeque — Mon, 11 May 2026 09:21:32 GMT

Hi AditiPattnaik

We wanted to follow up to check if you’ve had an opportunity to review the previous responses. If you require further assistance, please don’t hesitate to let us know.

Re: Deserialization error when publishing events to Eventstream via Event Grid after initial success

v-aatheeque — Wed, 13 May 2026 12:04:38 GMT

Have you had a chance to look through the responses shared earlier? If anything is still unclear, we’ll be happy to provide additional support.