Error retrieving the current token in a Blazor application after successful authentication in Azure B2C with Msal

This issue has been moved from a ticket on Developer Community.

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I have created a Blazor application and I use Msal to do authentication following the examples from Azure B2C. With my B2C configuration in the server, I can successfully login, I get the User, the claims and I can call the api. I would need to have access to the token during development to be able to use that token to call my api services directly using swagger. So during Debugging I wanted to print the token on screen to copy and paste.

However, when I try to get the token in the Client after successful login, I get an Exception: An exception occurred executing JS interop: The JSON value could not be converted to System.DateTimeOffset. Path: $.token.expires

This is a very confusing exception and doesn’t seem to explain the type of error that is occurring. It seems that is not doing any validation during the parsing or pre-parsing. So not sure why this is happening.

More details:

I initialise with this:

builder. Services.AddMsalAuthentication(options =>
            {
                builder. Configuration.Bind("AzureAdB2C", options. ProviderOptions.Authentication);

//options. ProviderOptions.DefaultAccessTokenScopes.Add("02200220-20202-2020-2020-202020200202002"); // I tried to put the application Id a per documentation and it doesn't work

options. ProviderOptions.DefaultAccessTokenScopes.Add("openid");
                options. ProviderOptions.DefaultAccessTokenScopes.Add("offline_access");

// request scope to access the API
                options. ProviderOptions.AdditionalScopesToConsent.Add("https://myb2c.onmicrosoft.com/whateverApp/MyAPI");

options. ProviderOptions.LoginMode = "redirect";
            });

I also use a custom AuthorizationMessageHandler to be able to call the api, which works well.

However, when in my code I call the code to retrieve the Token, I get the exception + one unhandled exception:

[Inject]
public IAccessTokenProvider TokenProvider { get; set; }
...
var accessTokenResult = await TokenProvider.RequestAccessToken(); // <-- This throws exception

And additionally there is an unhandled exception:

Unhandled Exception:
System.Text.Json.JsonException: Invalid JSON
   at Microsoft.JSInterop.Infrastructure.DotNetDispatcher.EndInvokeJS(JSRuntime jsRuntime, String arguments)
   at Microsoft.AspNetCore.Components.WebAssembly.Services.DefaultWebAssemblyJSRuntime.<>c.<EndInvokeJS> b__7_0(String argsJson)
   at Microsoft.AspNetCore.Components.WebAssembly.Hosting.WebAssemblyCallQueue.Schedule[String](String state, Action`1 callback)
   at Microsoft.AspNetCore.Components.WebAssembly.Services.DefaultWebAssemblyJSRuntime.EndInvokeJS(String argsJson)
Uncaught Error: System.Text.Json.JsonException: Invalid JSONThe thread 0x1b444 has exited with code 0 (0x0).

I have tried in B2C to set the configuration, and I’m able to run the SignIn flow redirecting to jwt.ms passing the token and decoding it.

And I get the token decoded when redirecting directly to jwt.ms:

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Original Comments

Feedback Bot on 11/12/2021, 00:15 AM:

We have directed your feedback to the appropriate engineering team for further evaluation. The team will review the feedback and notify you about the next steps.

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Original Solutions

(no solutions)

[kbeaugrand]

Hi @mkArtakMSFT @TanayParikh ,

I saw that nothing changed here (and I forget to push the sample repository).

This is available herehttps://github.com/kbeaugrand/SampleOpenIDConnect

I’m using Okta identity provider, the settings are present at Program.cs#L16-21

[abbasl7]

Do we have any known workaround to handle this issue till it is officially fixed?