Blazor server app not working when deployed, works fine in Visual Studio

Question

I have a Blazor server-side project which I've been developing in Visual Studio 2019, using .NET5. All has been working fine.

I've just deployed the site to a test server (which has two such sites already running on it, so I know the server has everything it needs to run the site), but none of the Blazor stuff seems to work. Specifically...

• Clicking on a button doesn't do anything
• Clicking on a link refreshes the entire page, instead of just rendering the new HTML
• Authorisation seems to be ignored, so a page with an [Authorize] attribute is visible to anyone

Don't know what code to show, as it all works when running in VS. Here is the contents of App.razor...

<CascadingAuthenticationState>
  <Router AppAssembly="@typeof(Program).Assembly">
    <Found Context="routeData">
      <AuthorizeRouteView RouteData="@routeData" DefaultLayout="@typeof(MainLayout)">
        <NotAuthorized>
          <RedirectToLogin />
        </NotAuthorized>
      </AuthorizeRouteView>
    </Found>
    <NotFound>
      <AuthorizeView>
        <Authorized>
          <LayoutView Layout="@typeof(MainLayout)">
            <NotFound />
          </LayoutView>
        </Authorized>
        <NotAuthorized>
          <RedirectToLogin />
        </NotAuthorized>
      </AuthorizeView>
    </NotFound>
  </Router>
</CascadingAuthenticationState>

The _Imports.razor file contains all the right usings, specifically including...

@using Microsoft.AspNetCore.Authorization
@using Microsoft.AspNetCore.Components.Authorization
@using Microsoft.AspNetCore.Components.Forms
@using Microsoft.AspNetCore.Components.Routing
@using Microsoft.AspNetCore.Components.Web

Pages that are not supposed to be accessible to non-logged-in users are decorated with [Authorize(Roles = "Admin")] in the code-behind or @attribute [Authorize(Roles = "Admin")] in the .razor file.

Anyone any ideas what I could have done wrong? Please advise if there is any more information I can give. Thanks

Update I just tried deploying the site to another domain on the same server, and it runs fine. I also tried pointing the other site to the folder for this one, and it worked fine (so it's not the deployed files), and then pointing this site to the other's folder, and it didn't work. So, it looks like there is something wrong with the site itself, but I ahve no idea what as it looks like the other.

Answer 1

It turned out that the problem was nothing to do with my code, nor my site settings on the server. I use Cloudflare, and had set it to minify HTML. This removes the two HTML comments that are essential for Blazor to work. See this article for more information.

So, if you are using Cloudflare, by all means set it to minify JavaScript and CSS, but DO not minify HTML.

Answer 2

If you're hosting your application on IIS and your Blazor is a Server Side project, make sure the WebSockets feature is enabled in the Add Roles and Features wizard by following this instructions.

Hope this helps someone

For reference => https://learn.microsoft.com/en-us/aspnet/core/blazor/host-and-deploy/server?view=aspnetcore-8.0#iis