[Pre4] NavigateTo no longer throws navigation exception (#35431)

Author: guardrex

aspnetcore/release-notes/aspnetcore-10/includes/blazor.md

@@ -367,4 +367,22 @@ In Blazor Web Apps, framework static assets are automatically preloaded using [`
 
 For more information, see <xref:blazor/fundamentals/static-files?view=aspnetcore-10.0#preloaded-blazor-framework-static-assets>.
 
+## `NavigationManager.NavigateTo` no longer throws a `NavigationException`
+
+Previously, calling <xref:Microsoft.AspNetCore.Components.NavigationManager.NavigateTo%2A?displayProperty=nameWithType> during static server-side rendering (SSR) would throw a <xref:Microsoft.AspNetCore.Components.NavigationException>, interrupting execution before being converted to a redirection response. This caused confusion during debugging and was inconsistent with interactive rendering, where code after <xref:Microsoft.AspNetCore.Components.NavigationManager.NavigateTo%2A> continues to execute normally.
+
+Calling <xref:Microsoft.AspNetCore.Components.NavigationManager.NavigateTo%2A?displayProperty=nameWithType> during static SSR no longer throws a <xref:Microsoft.AspNetCore.Components.NavigationException>. Instead, it behaves consistently with interactive rendering by performing the navigation without throwing an exception.
+
+Code that relied on <xref:Microsoft.AspNetCore.Components.NavigationException> being thrown should be updated. For example, in the default Blazor Identity UI, the `IdentityRedirectManager` previously threw an <xref:System.InvalidOperationException> after calling `RedirectTo` to ensure it wasn't invoked during interactive rendering. This exception and the [`[DoesNotReturn]` attributes](xref:System.Diagnostics.CodeAnalysis.DoesNotReturnAttribute) should now be removed.
+
+!!!!!!!!! HOLD THE NEXT BIT FOR PREVIEW 5 !!!!!!!!!
+To revert to the previous behavior of throwing a <xref:Microsoft.AspNetCore.Components.NavigationException>, set the following <xref:System.AppContext> switch:
+
+```csharp
+AppContext.SetSwitch(
+    "Microsoft.AspNetCore.Components.Endpoints.NavigationManager.EnableThrowNavigationException", 
+    isEnabled: true);
+```
+!!!!!!!!! HOLD END !!!!!!!!!
+
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