Design-time Preview fails: DI services (DialogService, IStringLocalizer) not registered in Radzen Preview host

[Agefer]

Hello,

I am experiencing an issue when Radzen Studio tries to render my custom MainLayout in design‑time preview. The application itself runs correctly in the browser, but Radzen Preview fails with the following exception:

System.InvalidOperationException: Cannot provide a value for property 'DialogService' on type 'EventsApproval.Components.Layout.MainLayout'. There is no registered service of type 'Radzen.DialogService'.
   at Microsoft.AspNetCore.Components.ComponentFactory...
   at Radzen.Server.RemoteRenderer.HandleException(Exception exception)
   at Radzen.Server.Router.Render(Type layout, Type component, Boolean renderLayout)
   at Radzen.Server.ProjectServer.Render(String fileName, String source, Boolean renderLayout)

In my actual Blazor Server application, all Radzen services are correctly registered in Program.cs:

builder.Services.AddScoped<DialogService>();
builder.Services.AddScoped<TooltipService>();
builder.Services.AddScoped<ContextMenuService>();
builder.Services.AddScoped<NotificationService>();

The application works without any errors when running normally. The problem occurs only inside Radzen Studio, which appears to use its own DI container and does not register Radzen services or localization services required by my layout.

As a result, Radzen Preview cannot instantiate my layout component and throws the exception above.

Could you please advise:

1. How to configure Radzen Studio so that design‑time rendering uses the same DI services as the actual application?

2. Or how to disable design‑time rendering for specific components/layouts to avoid these errors?

Thank you in advance.

[korchev]

Hi @Agefer,

Radzen Blazor Studio uses the same DI container as the app. Also those services are registered in every single Radzen Blazor app and work without issue. I suspect something else throws an exception before those services are registered. You can try moving this code up:

builder.Services.AddScoped<DialogService>();
builder.Services.AddScoped<TooltipService>();
builder.Services.AddScoped<ContextMenuService>();
builder.Services.AddScoped<NotificationService>();

You can also hide certain service registration code from the design time build.

[Agefer]

Dear @korchev ,

Thanks for the quick reply!

I found the commit after which Radzen Blazor Studio started throwing the error.

The screenshot shows that the Program.cs file was refactored: a partial class Program and an async Main method were introduced, and all application setup logic (builder creation, configuration, and service registrations) was moved inside this new Main method.

After reverting these changes, Radzen Blazor Studio stopped producing the error.

[korchev]

Hi @Agefer,

Can you prepare a minimal reproduction of this issue and send it to info@radzen.com? It sounds as a scenario that Radzen Blazor Studio should support out of the box.

[Agefer]

Dear @korchev .

Please find enclosed simple project with error.

Demo.zip (339.7 KB)

My Gmail doesn't want to attach the archive, even though I deleted the binaries.