Azure EventGrid MQTT Broker QuotaExceeded

Question

I'm building a service which connects to the MQTT broker service in Azure Event Grid.

It was connecting ok, but now I've started getting a QuotaExceeded response/exception when I try to connect a client for publishing. (I'm using MQTTNet, using Entra JWT authentication)

Nobody else is using it and the usage so far is minimal:

I tried increasing the the throughput units, but that changed nothing.

I've checked the quota limits outlined here and fail to see how I could be exceeding any of them.

Answer 1

Although I don't understand the cause of the issue, changing the client id / user served as a workaround

Answer 2

I was having a similar issue, for me the problem is that I set up 1 session per 1 client. When I first tested with Mqtt Explorer everything worked, later that I tested from mqttnet with the same client authentication name (username) but different clientID (session-identifier) and that error happened even though I had disconnected session from mqtt explorer already. I had to wait for a while then it worked again.