Скачать или смотреть Resolving the refresh_token Issue in Your Blazor Server App with Azure AD B2C

Discover how to fix the empty `refresh_token` issue in your Blazor Server App using Azure AD B2C authentication for seamless API access.
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This video is based on the question https://stackoverflow.com/q/74309698/ asked by the user 'Sam Vanhoutte' ( https://stackoverflow.com/u/2063902/ ) and on the answer https://stackoverflow.com/a/74315525/ provided by the user 'Nicola Biada' ( https://stackoverflow.com/u/11109967/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Understanding the refresh_token Issue in Blazor Server Apps with Azure AD B2C

If you're developing a Blazor Server App integrated with Azure AD B2C authentication, you might encounter a specific problem: the refresh_token in your application is empty, while the id_token successfully provides the JWT bearer token needed for API requests. This can be particularly troublesome since access tokens expire, and you need a proper method for obtaining a new one without prompting the user to log in again.

In this guide, we'll explore the cause of this issue and provide you with a clear, step-by-step solution to ensure that you can efficiently handle token refreshes in your Blazor Server App.

Problem Overview

Symptoms of the Issue

Empty refresh_token: When you try to access the refresh_token from HttpContext, it's empty.

Valid id_token: Your id_token is available and contains the JWT bearer token.

This creates a situation where, despite successful authentication, your app cannot automatically renew the access token when it expires.

Common Contexts Where This Happens

After a Token Expires: When the JWT token reaches its expiration limit (usually after an hour), you need a refresh_token to obtain a new valid token for API calls.

Using Azure AD B2C with OpenID Connect: If you're using the OpenID Connect protocol for authentication, misconfigurations in your setup can lead to this issue.

Finding the Solution

Here's how you can resolve the empty refresh_token problem in your Blazor Server App when using Azure AD B2C.

Step 1: Modify the ResponseType Configuration

Change your ResponseType: Update your ResponseType in your authentication setup as follows:

[[See Video to Reveal this Text or Code Snippet]]

The change from just CodeIdToken to CodeIdTokenToken indicates that your application should also request a refresh_token along with the other tokens. This is crucial for obtaining a valid refresh token.

Step 2: Update the Required Scopes

Add offline_access to your scopes: This scope is essential for receiving a refresh_token. Update your scope configuration as follows:

[[See Video to Reveal this Text or Code Snippet]]

The offline_access scope allows your application to obtain and use a refresh token, which keeps the user authenticated without needing to re-enter their credentials frequently.

Example Configuration

Here's how your configuration might look after making the updates:

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Step 3: Accessing Tokens Properly

After implementing the above changes, you should be able to retrieve the tokens properly:

[[See Video to Reveal this Text or Code Snippet]]

Conclusion

By following the above steps, you can effectively address the issue of having an empty refresh_token in your Blazor Server App while using Azure AD B2C Authentication. Remember to adjust your configuration settings to utilize the offline_access scope and modify the ResponseType as indicated. With these changes, your application will handle token refreshes smoothly, ensuring a better user experience without unnecessary interruptions.

Now you can enjoy a robust authentication flow in your Blazor Server App while leveraging Azure AD B2C effectively!