'HttpNavigationManager' not initialized when rendering static HTML

Question

I'm trying to generate HTML to a string from a Razor component. I use the following code to do that:

var html = await _htmlRenderer.Dispatcher.InvokeAsync(async () =>
        {
            var pv = ParameterView.FromDictionary(parameters);
            var output = await _htmlRenderer.RenderComponentAsync<TComponent>(pv);

            return output.ToHtmlString();
        });

It worked well, until I included a child component in the Razor component and try to render it. I got the following error:

'HttpNavigationManager' has not been initialized

I don't use any navigation logic in the parent, nor in the child component. How can it be fixed?

@GuidoNeele Yes, actually it has. What's "wrong" with that? How do that cause the error? — Erik Z
– Erik Z, Commented Apr 22 at 4:27

Guido Neele · Accepted Answer · 2025-04-23 08:45:01Z

1

If your component has a Form tag without an action attribute the Razor renderer is trying to set the action to the current route. But since you are using static rendering the HtmlNavigationManager isn't initialized, which is used to set the route of the action attribute. You can prevent this by setting the action attribute yourself, maybe a # is enough (haven't tried that myself)

answered Apr 23 at 8:45

Guido Neele

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2 Comments

Erik Z Apr 29 at 6:46

Great explanation. Is it possible to manually initlialize the HtmlNavigationManager?

Guido Neele Apr 30 at 7:10

You can probably add ` services.AddScoped<NavigationManager, HttpNavigationManager>();` to your Program.cs

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