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Hosting model-agnostic Prerender section (#24211)

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aspnetcore/blazor/fundamentals/handle-errors.md
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@ -384,7 +384,7 @@ The following conditions apply to error handling with <xref:Microsoft.JSInterop.
Similarly, JavaScript code may initiate calls to .NET methods indicated by the [`[JSInvokable]` attribute](xref:blazor/js-interop/call-dotnet-from-javascript). If these .NET methods throw an unhandled exception:
* In a Blazor Server app, the exception is ***not** treated as fatal to the app's circuit.
* In a Blazor Server app, the exception is ***not*** treated as fatal to the app's circuit.
* The JavaScript-side `Promise` is rejected.
You have the option of using error handling code on either the .NET side or the JavaScript side of the method call.
@ -396,22 +396,27 @@ For more information, see the following articles:
### Prerendering
*This section applies to Blazor Server apps.*
Blazor components can be prerendered using the [Component Tag Helper](xref:mvc/views/tag-helpers/builtin-th/component-tag-helper) so that their rendered HTML markup is returned as part of the user's initial HTTP request.
Blazor components can be prerendered using the [Component Tag Helper](xref:mvc/views/tag-helpers/builtin-th/component-tag-helper) so that their rendered HTML markup is returned as part of the user's initial HTTP request. This works by:
In Blazor Server, prerendering works by:
* Creating a new circuit for all of the prerendered components that are part of the same page.
* Generating the initial HTML.
* Treating the circuit as `disconnected` until the user's browser establishes a SignalR connection back to the same server. When the connection is established, interactivity on the circuit is resumed and the components' HTML markup is updated.
If any component throws an unhandled exception during prerendering, for example, during a lifecycle method or in rendering logic:
In prerendered Blazor WebAssembly, prerendering works by:
* The exception is fatal to the circuit.
* The exception is thrown up the call stack from the <xref:Microsoft.AspNetCore.Mvc.TagHelpers.ComponentTagHelper> Tag Helper. Therefore, the entire HTTP request fails unless the exception is explicitly caught by developer code.
* Generating initial HTML on the server for all of the prerendered components that are part of the same page.
* Making the component interactive on the client after the browser has loaded the app's compiled code and the .NET runtime (if not already loaded) in the background.
If a component throws an unhandled exception during prerendering, for example, during a lifecycle method or in rendering logic:
* In Blazor Sever apps, the exception is fatal to the circuit. In prerendered Blazor WebAssembly apps, the exception prevents rendering the component.
* The exception is thrown up the call stack from the <xref:Microsoft.AspNetCore.Mvc.TagHelpers.ComponentTagHelper>.
Under normal circumstances when prerendering fails, continuing to build and render the component doesn't make sense because a working component can't be rendered.
To tolerate errors that may occur during prerendering, error handling logic must be placed inside a component that may throw exceptions. Use [`try-catch`](/dotnet/csharp/language-reference/keywords/try-catch) statements with error handling and logging. Instead of wrapping the <xref:Microsoft.AspNetCore.Mvc.TagHelpers.ComponentTagHelper> Tag Helper in a [`try-catch`](/dotnet/csharp/language-reference/keywords/try-catch) statement, place error handling logic in the component rendered by the <xref:Microsoft.AspNetCore.Mvc.TagHelpers.ComponentTagHelper> Tag Helper.
To tolerate errors that may occur during prerendering, error handling logic must be placed inside a component that may throw exceptions. Use [`try-catch`](/dotnet/csharp/language-reference/keywords/try-catch) statements with error handling and logging. Instead of wrapping the <xref:Microsoft.AspNetCore.Mvc.TagHelpers.ComponentTagHelper> in a [`try-catch`](/dotnet/csharp/language-reference/keywords/try-catch) statement, place error handling logic in the component rendered by the <xref:Microsoft.AspNetCore.Mvc.TagHelpers.ComponentTagHelper>.
## Advanced scenarios