Prerendered hosted Blazor WebAssembly errors not addressed by guidance

[guardrex]

Is there an existing issue for this?

• I have searched the existing issues

Describe the bug

We maintain prerendering guidance for hosted Blazor WebAssembly at ...

https://learn.microsoft.com/en-us/aspnet/core/blazor/components/prerendering-and-integration?view=aspnetcore-7.0&pivots=webassembly#prerendering-configuration

The guidance generally works as provided, but there are (at least) two bugs reported by @Krangth on dotnet/AspNetCore.Docs#28443 that crop up with use of our guidance that I think we'll need to react to somehow, either by calling out the reason for them (at least) or by calling out the situation(s) with modifications to our guidance to solve the problems ...

And if the user reloads any page, except the home page, a 404 error appears. Is that expected? That means a user wouldn't be able to share a link.

Error 1: Reloading a page with Blazor's HttpClient in use (e.g., the FetchData page)

When reloading the FetchData page or opening another browser and attempting to navigate directly to the FetchData page, @Krangth and I get ...

System.InvalidOperationException: Cannot provide a value for property 'Http' on type 'BlazorHosted.Client.Pages.FetchData'. There is no registered service of type 'System.Net.Http.HttpClient'.
   at Microsoft.AspNetCore.Components.ComponentFactory.<>c__DisplayClass7_0.<CreateInitializer>g__Initialize|1(IServiceProvider serviceProvider, IComponent component)
   at Microsoft.AspNetCore.Components.ComponentFactory.PerformPropertyInjection(IServiceProvider serviceProvider, IComponent instance)
   at Microsoft.AspNetCore.Components.ComponentFactory.InstantiateComponent(IServiceProvider serviceProvider, Type componentType)
   at Microsoft.AspNetCore.Components.RenderTree.Renderer.InstantiateChildComponentOnFrame(RenderTreeFrame& frame, Int32 parentComponentId)
   at Microsoft.AspNetCore.Components.RenderTree.RenderTreeDiffBuilder.InitializeNewComponentFrame(DiffContext& diffContext, Int32 frameIndex)
   at Microsoft.AspNetCore.Components.RenderTree.RenderTreeDiffBuilder.InitializeNewSubtree(DiffContext& diffContext, Int32 frameIndex)
   at Microsoft.AspNetCore.Components.RenderTree.RenderTreeDiffBuilder.InsertNewFrame(DiffContext& diffContext, Int32 newFrameIndex)
   at Microsoft.AspNetCore.Components.RenderTree.RenderTreeDiffBuilder.AppendDiffEntriesForRange(DiffContext& diffContext, Int32 oldStartIndex, Int32 oldEndIndexExcl, Int32 newStartIndex, Int32 newEndIndexExcl)
   at Microsoft.AspNetCore.Components.RenderTree.RenderTreeDiffBuilder.ComputeDiff(Renderer renderer, RenderBatchBuilder batchBuilder, Int32 componentId, ArrayRange`1 oldTree, ArrayRange`1 newTree)
   at Microsoft.AspNetCore.Components.Rendering.ComponentState.RenderIntoBatch(RenderBatchBuilder batchBuilder, RenderFragment renderFragment, Exception& renderFragmentException)
   at Microsoft.AspNetCore.Components.RenderTree.Renderer.ProcessRenderQueue()
--- End of stack trace from previous location ---
   at Microsoft.AspNetCore.Components.RenderTree.Renderer.ProcessRenderQueue()
   at Microsoft.AspNetCore.Components.RenderTree.Renderer.AddToRenderQueue(Int32 componentId, RenderFragment renderFragment)
   at Microsoft.AspNetCore.Components.ComponentBase.StateHasChanged()
   at Microsoft.AspNetCore.Components.ComponentBase.CallOnParametersSetAsync()
   at Microsoft.AspNetCore.Components.ComponentBase.RunInitAndSetParametersAsync()
   at Microsoft.AspNetCore.Components.RenderTree.Renderer.RenderRootComponentAsync(Int32 componentId, ParameterView initialParameters)
   at Microsoft.AspNetCore.Components.Rendering.HtmlRenderer.RenderComponentAsync(Type componentType, ParameterView initialParameters)
   at Microsoft.AspNetCore.Components.Rendering.RendererSynchronizationContext.<>c__11`1.<<InvokeAsync>b__11_0>d.MoveNext()
--- End of stack trace from previous location ---
   at Microsoft.AspNetCore.Mvc.ViewFeatures.StaticComponentRenderer.PrerenderComponentAsync(ParameterView parameters, HttpContext httpContext, Type componentType)
   at Microsoft.AspNetCore.Mvc.ViewFeatures.ComponentRenderer.PrerenderedWebAssemblyComponentAsync(HttpContext context, Type type, ParameterView parametersCollection)
   at Microsoft.AspNetCore.Mvc.ViewFeatures.ComponentRenderer.RenderComponentAsync(ViewContext viewContext, Type componentType, RenderMode renderMode, Object parameters)
   at Microsoft.AspNetCore.Mvc.TagHelpers.ComponentTagHelper.ProcessAsync(TagHelperContext context, TagHelperOutput output)
   at Microsoft.AspNetCore.Razor.Runtime.TagHelpers.TagHelperRunner.<RunAsync>g__Awaited|0_0(Task task, TagHelperExecutionContext executionContext, Int32 i, Int32 count)
   at BlazorHosted.Server.Pages.Pages__Host.<ExecuteAsync>b__14_1() in C:\Users\guard\OneDrive\Desktop\BlazorHosted\Server\Pages\_Host.cshtml:line 20
   at Microsoft.AspNetCore.Razor.Runtime.TagHelpers.TagHelperExecutionContext.SetOutputContentAsync()
   at BlazorHosted.Server.Pages.Pages__Host.ExecuteAsync()
   at Microsoft.AspNetCore.Mvc.Razor.RazorView.RenderPageCoreAsync(IRazorPage page, ViewContext context)
   at Microsoft.AspNetCore.Mvc.Razor.RazorView.RenderPageAsync(IRazorPage page, ViewContext context, Boolean invokeViewStarts)
   at Microsoft.AspNetCore.Mvc.Razor.RazorView.RenderAsync(ViewContext context)
   at Microsoft.AspNetCore.Mvc.ViewFeatures.ViewExecutor.ExecuteAsync(ViewContext viewContext, String contentType, Nullable`1 statusCode)
   at Microsoft.AspNetCore.Mvc.ViewFeatures.ViewExecutor.ExecuteAsync(ViewContext viewContext, String contentType, Nullable`1 statusCode)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeNextResultFilterAsync>g__Awaited|30_0[TFilter,TFilterAsync](ResourceInvoker invoker, Task lastTask, State next, Scope scope, Object state, Boolean isCompleted)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.Rethrow(ResultExecutedContextSealed context)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.ResultNext[TFilter,TFilterAsync](State& next, Scope& scope, Object& state, Boolean& isCompleted)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.InvokeResultFilters()
--- End of stack trace from previous location ---
   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeNextResourceFilter>g__Awaited|25_0(ResourceInvoker invoker, Task lastTask, State next, Scope scope, Object state, Boolean isCompleted)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.Rethrow(ResourceExecutedContextSealed context)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.Next(State& next, Scope& scope, Object& state, Boolean& isCompleted)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.InvokeFilterPipelineAsync()
--- End of stack trace from previous location ---
   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeAsync>g__Awaited|17_0(ResourceInvoker invoker, Task task, IDisposable scope)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeAsync>g__Awaited|17_0(ResourceInvoker invoker, Task task, IDisposable scope)
   at Microsoft.AspNetCore.Routing.EndpointMiddleware.<Invoke>g__AwaitRequestTask|6_0(Endpoint endpoint, Task requestTask, ILogger logger)
   at Microsoft.AspNetCore.Authorization.AuthorizationMiddleware.Invoke(HttpContext context)
   at Microsoft.AspNetCore.Authentication.AuthenticationMiddleware.Invoke(HttpContext context)
   at Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddlewareImpl.Invoke(HttpContext context)

Error 2: Reloading another page too rapidly (e.g., the Counter page)

When reloading rapidly on the Counter page, we see a client-side console error that breaks the page. Reloading once gets the page running again. Navigating to the Index page and back gets the page working again. Navigating directly to the FetchData page after the error produces Error 1 ☝️. Reloading at a medium rate produces the following error intermittently. Relatively slow reloads are fine.

System.AggregateException: One or more errors occurred. (error loading dynamically imported module
---> Microsoft.JSInterop.JSException: error loading dynamically imported module

at Microsoft.JSInterop.JSRuntime.d__16`1[[Microsoft.JSInterop.IJSObjectReference, Microsoft.JSInterop, Version=7.0.0.0, Culture=neutral, PublicKeyToken=adb9793829ddae60]].MoveNext()
at Microsoft.AspNetCore.Components.WebAssembly.HotReload.WebAssemblyHotReload.InitializeAsync()
at Microsoft.AspNetCore.Components.WebAssembly.Hosting.WebAssemblyHost.RunAsyncCore(CancellationToken cancellationToken, WebAssemblyCultureProvider cultureProvider)
at Program.

$(String[] args)
--- End of inner exception stack trace ---

Expected Behavior

I think we'll either need to call out what's happening and why, or we'll need to fix these problems in the guidance to avoid/prevent them.

Steps To Reproduce

Follow the guidance at https://learn.microsoft.com/en-us/aspnet/core/blazor/components/prerendering-and-integration?view=aspnetcore-7.0&pivots=webassembly#prerendering-configuration.

I've placed a repro project that exactly follows our guidance here ...

https://github.com/guardrex/BlazorHosted_Prerendered

Exceptions (if any)

Shown above ☝️.

.NET Version

7.0.200-preview.22628.1

Anything else?

ASP.NET Core version: 7.0.x

IDE: VS

dotnet --info output:

7.0.200-preview.22628.1
.NET SDK:
Version: 7.0.200-preview.22628.1
Commit: 76bbaffad6

Runtime Environment:
OS Name: Windows
OS Version: 10.0.22621
OS Platform: Windows
RID: win10-x64
Base Path: C:\Program Files\dotnet\sdk\7.0.200-preview.22628.1\

Host:
Version: 7.0.3
Architecture: x64
Commit: 0a2bda10e8

.NET SDKs installed:
5.0.214 [C:\Program Files\dotnet\sdk]
6.0.309 [C:\Program Files\dotnet\sdk]
7.0.103 [C:\Program Files\dotnet\sdk]
7.0.200-preview.22628.1 [C:\Program Files\dotnet\sdk]

.NET runtimes installed:
Microsoft.AspNetCore.App 5.0.17 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 6.0.12 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 6.0.14 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 7.0.0 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 7.0.3 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.NETCore.App 5.0.17 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 6.0.12 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 6.0.14 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 7.0.0 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 7.0.3 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.WindowsDesktop.App 5.0.17 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
Microsoft.WindowsDesktop.App 6.0.12 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
Microsoft.WindowsDesktop.App 6.0.14 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
Microsoft.WindowsDesktop.App 7.0.0 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
Microsoft.WindowsDesktop.App 7.0.3 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]

Other architectures found:
x86 [C:\Program Files (x86)\dotnet]
registered at [HKLM\SOFTWARE\dotnet\Setup\InstalledVersions\x86\InstallLocation]

Environment variables:
Not set

global.json file:
Not found

Thanks for contacting us.

We're moving this issue to the .NET 8 Planning milestone for future evaluation / consideration. We would like to keep this around to collect more feedback, which can help us with prioritizing this work. We will re-evaluate this issue, during our next planning meeting(s).
If we later determine, that the issue has no community involvement, or it's very rare and low-impact issue, we will close it - so that the team can focus on more important and high impact issues.
To learn more about what to expect next and how this issue will be handled you can read more about our triage process here.

[guardrex]

@mkArtakMSFT @surayya-MS ... Since hosted WASM is going away, these problems with prerendered hosted WASM go away at >=8.0. All of the content on this matter in the Prerendering and integration article will go away. Do you still plan to work these problems for <8.0 releases, or do you want to close this as a won't-fix scenario for <8.0? If you close this, do you want the <8.0 content of the article to avoid commenting on these problems, or do you want the content to note these problems in passing, mentioning that they won't be investigated/fixed due to the loss of the hosting option in >=8.0?

Thanks for contacting us.

We're moving this issue to the .NET 9 Planning milestone for future evaluation / consideration. We would like to keep this around to collect more feedback, which can help us with prioritizing this work. We will re-evaluate this issue, during our next planning meeting(s).
If we later determine, that the issue has no community involvement, or it's very rare and low-impact issue, we will close it - so that the team can focus on more important and high impact issues.
To learn more about what to expect next and how this issue will be handled you can read more about our triage process here.