Blazor Server exception when using SignalR with AAD authentication

[ElBertrando]

I am using the tutorial here:
https://docs.microsoft.com/en-us/aspnet/core/tutorials/signalr-blazor?view=aspnetcore-5.0&tabs=visual-studio&pivots=server
in visual studio 2019. I then add Azure authentication to the code and add the correct Instance, Domain, TenantId, ClientId, CallbackPath in appsettings.json.

When i run the code I get exception error in the browser:

JsonReaderException: '<' is an invalid start of a value. LineNumber: 2 | BytePositionInLine: 0.

InvalidDataException: Invalid negotiation response received

Describe the bug

Adding AAD to the code with signalR connection produces exception.

To Reproduce

Relevant part of code:

    protected override async Task OnInitializedAsync()
    {
        _hubConnection = new HubConnectionBuilder()
            .WithUrl(NavigationManager.ToAbsoluteUri("/chathub"))
            .Build();

        _hubConnection.On<string, string>("ReceiveMessage", (user, message) =>
        {
            var encodedMsg = $"{user}: {message}";
            _messages.Add(encodedMsg);
            StateHasChanged();
        });

        await _hubConnection.StartAsync();
    }

Exceptions (if any)

JsonReaderException: '<' is an invalid start of a value. LineNumber: 2 | BytePositionInLine: 0.

System.Text.Json.ThrowHelper.ThrowJsonReaderException(ref Utf8JsonReader json, ExceptionResource resource, byte nextByte, ReadOnlySpan<byte> bytes)

InvalidDataException: Invalid negotiation response received.

Microsoft.AspNetCore.Http.Connections.NegotiateProtocol.ParseResponse(ReadOnlySpan<byte> content)

Further technical details

• ASP.NET Core version: 5.0
• The IDE (VS / VS Code/ VS4Mac) you're running on, and its version: Visual Studio 2019 version 16.11.5
• Include the output of dotnet --info:
• .NET SDK (reflecting any global.json):
  Version: 5.0.402
  Commit: e9d3381880

Runtime Environment:
OS Name: Windows
OS Version: 10.0.19043
OS Platform: Windows
RID: win10-x64
Base Path: C:\Program Files\dotnet\sdk\5.0.402\

Host (useful for support):
Version: 5.0.11
Commit: f431858f8b

.NET SDKs installed:
5.0.102 [C:\Program Files\dotnet\sdk]
5.0.402 [C:\Program Files\dotnet\sdk]

.NET runtimes installed:
Microsoft.AspNetCore.All 2.1.30 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
Microsoft.AspNetCore.App 2.1.30 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 3.1.20 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 5.0.11 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.NETCore.App 2.1.30 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 3.1.20 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 5.0.11 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.WindowsDesktop.App 3.1.20 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
Microsoft.WindowsDesktop.App 5.0.11 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]

To install additional .NET runtimes or SDKs:
https://aka.ms/dotnet-download

[TanayParikh]

Looks like this may be a duplicate of: #11274

[ElBertrando]

I am developing locally to test . Also, I should add that running the default blazor application works with AAD in our environment. Only when I add the "chathub" functionality does it fail.

[javiercn]

@ElBertrando thanks for contacting us.

If you are using Blazor Server you need to keep in mind that you are connecting to the hub from within the server and not the browser, and the server doesn't have the credentials required to connect to the hub (since those come from the cookie the browser sends).

In this context you need to envision a different solution to connect to the server hub (since you are technically doing a server to server connection).

[ElBertrando]

@javiercn I tested with IT that the default code from a Blazor server application works with AAD running from my local machine. Only when I change the code for the chat application using signalR do I experience this issue.

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