Antiforgery token is not being generated

Question

I'm using Blazor (Interactive Server) to create a web application. Before I went on holiday I used the general template available in Visual Studio 2022, including the authentication & authorization options, as an example for creating the application.

Now that I'm back I need to start continuing this project. However, handling forms do not work anymore, giving me A valid antiforgery token was not provided with the request. Add an antiforgery token, or disable antiforgery validation for this endpoint. when submitting the login form.

Bypassing this check by adding DisableAntiforgery() to the app.MapRazorComponents<App>() in program.cs did work to login. I enabled antiforgery again and found out that all forms do not work anymore, such as the registration form and the logout-redirect (which is using a post-method, copied from the template).

Diving into the generated HTML of the forms, I saw that the hidden input form field _requestVerificationToken is not generated, despite including <AntiforgeryToken /> in the blazor code form for the logout-button. The same is happening in the <EditForm>-forms, also there no token is being generated for the HTML.

The only solutions I have found is disabling the antiforgery (which I did to bypass), but this could become a security risk. Deleting app.UseAntiforgery() is not possible, as then Authentication and Authorization do not work anymore. Other suggestions include the location of app.UseAntiforgery() in the program.cs file, which I already placed after app.UseAuthentication() and app.UseAuthorization().

I really cannot find any reason why this is not working anymore: I had no problems with the antiforgery tokens a couple of weeks ago. Removing the global authorization requirement or disabling the <AuthorizeView> elements also do nothing.

I also tried reverting back to an earlier state where Authentication and Authorization were not used, to test again. This also did not work, as it is too integrated once enabled.

Answer 1

1. Check Startup.cs Configuration: Ensure that your middleware configuration in Startup.cs (or Program.cs in .NET 6 onwards) is correct. The order of middleware is crucial. UseAuthentication(), UseAuthorization(), and UseAntiforgery() should be properly configured. Typically, UseRouting(), UseAuthentication(), and UseAuthorization() need to be called in this order before UseEndpoints().

   
      app.UseRouting();
   
      app.UseAuthentication();
   
      app.UseAuthorization();
   
      app.UseEndpoints(endpoints =>
   
      {
   
          endpoints.MapRazorPages();
   
          endpoints.MapBlazorHub();
   
          endpoints.MapFallbackToPage("/_Host");
   
      });
   
   

2. Ensure Antiforgery Token Initialization: In Blazor Server, you might not see a direct way to work with antiforgery tokens like you would in an MVC or Razor Pages application. However, ensure that any Razor page handling form submissions initializes the antiforgery token. If you are using Razor pages for the forms, you can manually add @Html.AntiForgeryToken() in your form.
3. Verify Blazor Server Configuration: Since Blazor Server works differently compared to traditional web apps, check if there are any specific settings or configurations altered that might affect token generation. Make sure that the <AntiforgeryToken /> component you're using is correctly implemented or referenced, as this is not a standard Blazor component.
4. Investigate External Changes: Since you mentioned that the issue arose after a break, check if there have been updates to the Blazor framework, libraries, or the browser that could affect how sessions and tokens are handled. Sometimes, browser updates can affect how cookies and headers are managed.
5. Logging and Debugging: Add extensive logging around the point where the form is submitted and where you expect the token to be validated. This might give you more insight into what is going wrong. You can use tools like Fiddler or Chrome Developer Tools to inspect the requests being sent and ensure that tokens are being transmitted correctly.
6. Test in Different Environments: If possible, test the application in a different environment or machine to see if the issue persists. This can help isolate the problem to environment-specific configurations or setups.
7. Review Changes: Review any code changes made before the issue appeared. If you're using version control like Git, consider checking out a previous commit where the feature was known to work and compare the current state.
8. Community and Support: If the issue persists, consider reaching out to the community through forums like Stack Overflow or the official Blazor GitHub repository. There might be others who have faced similar issues or updates in the framework that addressed such problems.

By following these steps, you should be able to diagnose why the antiforgery token is not being generated and apply a suitable fix.