Azure SignalR React Library to Azure serverless SignalR throw 401 - "The signature key was not found"

[humzatufail47]

Describe the bug

We’re intermittently encountering 401 responses when making calls to the Azure SignalR service from our React library. These errors are inconsistent—some requests return 200 OK while others fail with 401 Unauthorized, even within the same session. We've observed the same behavior during testing in Postman. This issue first occurred in our production environment on May 1st, and again across all environments (dev, test, and prod) on May 9th. In both cases, the issue was only resolved after restarting the SignalR service.

To Reproduce

We don’t have specific steps to reproduce the issue, as it occurs randomly, most frequently in our test environment. However, restarting the SignalR service consistently resolves the problem temporarily.

Exceptions (if any)

Further technical details

• In APIs, we are using Microsoft.Azure.SignalR.Management version '1.30.2'.
• At the Client side, we are using @microsoft/signalr version '8.0.0' .
• APIs are built on top of .NET 9.
• We are using Managed Identity to authenticate our APIs with Azure serverless SignalR service.

[vicancy]

Hi @humzatufail47 could you email me lianwei<at>microsoft.com your client HAR file containing such 401 request?