Azure SignalR Service randomly drops connections immediately after successful connect

Describe the bug

We have 4 virtually identical Azure SignalR services and two of them are behaving badly. Using the same client and hub, I can connect to two of them without issues. The other two have been exhibiting a strange bug since about Thursday/Friday last week where the client will often connect (via the Hub) and then instantly disconnect with the error:

Microsoft.AspNetCore.SignalR.HubException: The server closed the connection with the following error: Connection closed with an error.

If the client retries, sometimes up to 10 or more times it will eventually reconnect successfully and then work as expected.

We are not hitting any service limits, we are currently using the “Standard” size although they are not used in production (yet), but we need to get to the bottom of the issue to know that this won’t happen again.

To Reproduce

I can email details on how to connect to our API with a reproducible code sample on request.

Exceptions (if any)

Microsoft.AspNetCore.SignalR.HubException: The server closed the connection with the following error: Connection closed with an error.

Further technical details

• Microsoft.AspNetCore.SignalR.Client v5.0.11
• Microsoft.AspNetCore.SignalR.Core v1.1.0

[schotime]

Ok, turns out mine was that the message exceeded 32KB, and I had to turn EnableDetailedErrors on to find the actual error.

[schotime]

I’ve just been getting this today, and I think i’ve had it other times too. Did anything come of this? This is also Australia East