Solving the Infamous Error AADSTS50049: “Unknown or invalid instance” in ASP.NET Core 8 MVC with Azure AD B2C

Are you tired of banging your head against the wall, trying to figure out why your Azure AD B2C authentication is throwing the dreaded Error AADSTS50049? Well, put down that aspirin and take a deep breath, because you’re in the right place! In this article, we’ll dive into the world of ASP.NET Core 8 MVC and Azure AD B2C, and I’ll guide you through the process of identifying and fixing this pesky error once and for all.

What is Error AADSTS50049?

Before we jump into the solution, let’s take a step back and understand what this error is all about. Error AADSTS50049 is a generic error message thrown by Azure AD B2C when it encounters an issue while trying to authenticate a user. It can occur due to various reasons, such as:

• Incorrect or malformed Azure AD B2C instance configuration
• Invalid or missing Azure AD B2C tenant ID
• Misconfigured Azure AD B2C policies
• Incorrect Azure AD B2C client ID or secret
• Network connectivity issues

Prerequisites

Before we begin, make sure you have the following:

• ASP.NET Core 8 MVC project set up with Azure AD B2C integration
• Azure AD B2C tenant created and configured
• Azure AD B2C client ID and secret
• Azure AD B2C policies created and configured

Troubleshooting Steps

Now, let’s get down to business! Follow these step-by-step instructions to identify and fix theError AADSTS50049:

Step 1: Verify Azure AD B2C Instance Configuration

Double-check that your Azure AD B2C instance is correctly configured in your ASP.NET Core 8 MVC project. Make sure you have the correct:

• Tenant ID
• Client ID
• Client secret
• Policies (sign-up, sign-in, and password reset)

services.AddAuthentication(options =>
{
    options.DefaultScheme = "Cookies";
    options.DefaultChallengeScheme = "OpenIdConnect";
})
.AddCookie("Cookies")
.AddOpenIdConnect("oidc", options =>
{
    options.Authority = "https://your-tenant-name.b2clogin.com/your-tenant-name.onmicrosoft.com/v2.0/";
    options.ClientId = "your-client-id";
    options.ClientSecret = "your-client-secret";
    options.ResponseType = "code id_token";
    options.SaveTokens = true;
});

Step 2: Check Azure AD B2C Tenant ID and Client ID

Verify that your Azure AD B2C tenant ID and client ID are correct and match the configuration in your ASP.NET Core 8 MVC project. You can find this information in the Azure portal:

• Tenant ID: Azure AD B2C > Overview > Tenant ID
• Client ID: Azure AD B2C > App registrations > Your application > Overview > Application (client) ID

Step 3: Review Azure AD B2C Policies

Make sure your Azure AD B2C policies are correctly configured and match the policies specified in your ASP.NET Core 8 MVC project. Check the following policies:

• Sign-up policy: Azure AD B2C > Identity Experience Framework > Policies > Sign-up policies
• Sign-in policy: Azure AD B2C > Identity Experience Framework > Policies > Sign-in policies
• Password reset policy: Azure AD B2C > Identity Experience Framework > Policies > Password reset policies

services.AddAuthentication(options =>
{
    options.DefaultScheme = "Cookies";
    options.DefaultChallengeScheme = "OpenIdConnect";
})
.AddCookie("Cookies")
.AddOpenIdConnect("oidc", options =>
{
    options.Authority = "https://your-tenant-name.b2clogin.com/your-tenant-name.onmicrosoft.com/v2.0/";
    options.ClientId = "your-client-id";
    options.ClientSecret = "your-client-secret";
    options.ResponseType = "code id_token";
    options.SaveTokens = true;
    options.Events = new OpenIdConnectEvents
    {
        OnRedirectToIdentityProvider = async context =>
        {
            context.ProtocolMessage.UiLocale = "en-US";
            await Task.CompletedTask;
        }
    };
    options.TokenValidationParameters = new TokenValidationParameters
    {
        ValidateIssuer = true,
        ValidIssuer = $"https://your-tenant-name.b2clogin.com/{your-tenant-id}/v2.0/",
        ValidateAudience = true,
        ValidAudience = $"https://your-tenant-name.b2clogin.com/{your-tenant-id}/",
        ValidateLifetime = true,
    };
});

Step 4: Check Network Connectivity

Verify that your network connection is stable and you can reach the Azure AD B2C instance. Try pinging the Azure AD B2C endpoint to check connectivity:

ping your-tenant-name.b2clogin.com

Common Scenarios and Solutions

Here are some common scenarios and solutions to help you troubleshoot the Error AADSTS50049:

Scenario 1: Invalid Azure AD B2C Tenant ID

Solution: Double-check the Azure AD B2C tenant ID in your ASP.NET Core 8 MVC project configuration and ensure it matches the tenant ID in the Azure portal.

Scenario 2: Misconfigured Azure AD B2C Policies

Solution: Review the Azure AD B2C policies and ensure they are correctly configured and match the policies specified in your ASP.NET Core 8 MVC project.

Scenario 3: Incorrect Azure AD B2C Client ID or Secret

Solution: Verify the Azure AD B2C client ID and secret in your ASP.NET Core 8 MVC project configuration and ensure they match the client ID and secret in the Azure portal.

Scenario 4: Network Connectivity Issues

Solution: Check the network connectivity and ensure you can reach the Azure AD B2C instance. Try pinging the Azure AD B2C endpoint to check connectivity.

Conclusion

And there you have it! By following these steps and scenarios, you should be able to identify and fix the Error AADSTS50049 in your ASP.NET Core 8 MVC application with Azure AD B2C. Remember to double-check your configuration, tenant ID, client ID, and policies, and ensure a stable network connection. If you’re still stuck, feel free to leave a comment below, and I’ll do my best to help you out!

Troubleshooting Step	Solution
Verify Azure AD B2C instance configuration	Check tenant ID, client ID, client secret, and policies in ASP.NET Core 8 MVC project
Check Azure AD B2C tenant ID and client ID	Verify tenant ID and client ID in Azure portal and ASP.NET Core 8 MVC project
Review Azure AD B2C policies	Check sign-up, sign-in, and password reset policies in Azure AD B2C and ASP.NET Core 8 MVC project
Check network connectivity	Verify stable network connection and ping Azure AD B2C endpoint

If you’re still experiencing issues, consider checking the Azure AD B2C documentation and ASP.NET Core 8 MVC documentation for more information on configuring Azure AD B2C authentication.

Happy coding, and I hope this article has saved you from the clutches of Error AADSTS50049!

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