Attempts to map multiple blazor entry points with MapBlazorHub causes Ambiguous Route Error. This worked with net7.

[ViperElectric]

Is there an existing issue for this?

• I have searched the existing issues

Describe the bug

It looks like attempts to use MapBlazorHub more than once in an Iappicationbuilder now cause an ambiguous route error.

app.UseDeveloperExceptionPage();
app.UseMiddleware<CheckPathMiddleware>();
app.UseStaticFiles();
app.UseInvariantCulture();
app.UseRouting();
app.UseEndpoints(x =>
{
    x.MapControllers();
    x.MapRazorPages();
    x.MapBlazorHub("/Instrument/_blazor");
    x.MapBlazorHub("/App/_blazor");
    x.MapFallbackToPage("/Web");
});

This is my code where I call MapBlazorHub, this worked in .net6 and .net7 but now when I run my code with this I get an AmbiguousMatchException Error that mentions "Blazor static files"

From my digging it seems like the MapBlazorHub now maps an enpoint for _framework/blazor.server.js but because I'm calling MapBlazorHub twice it's mapping a duplicate enpoint which breaks the application.

This is an application that runs on a piece of hardware with a display and we are using the /Instrument endpoint for the display output on the hardware and the App endpoint for a webpage that can be reached via USB.

Expected Behavior

I would expect that if MapBlazorHub is called more than once the _framework/blazor.server.js endpoint would not be mapped twice to prevent this duplicate route issue.

Steps To Reproduce

Call MapBlazorHub on two different entry points after updating to .net8

Exceptions (if any)

Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware: Error: An unhandled exception has occurred while executing the request.

Microsoft.AspNetCore.Routing.Matching.AmbiguousMatchException: The request matched multiple endpoints. Matches:

Blazor static files
Blazor static files
at Microsoft.AspNetCore.Routing.Matching.DefaultEndpointSelector.ReportAmbiguity(Span1 candidateState) at Microsoft.AspNetCore.Routing.Matching.DefaultEndpointSelector.ProcessFinalCandidates(HttpContext httpContext, Span1 candidateState)
at Microsoft.AspNetCore.Routing.Matching.DefaultEndpointSelector.Select(HttpContext httpContext, Span`1 candidateState)
at Microsoft.AspNetCore.Routing.Matching.DefaultEndpointSelector.SelectAsync(HttpContext httpContext, CandidateSet candidateSet)
at Microsoft.AspNetCore.Routing.Matching.DfaMatcher.SelectEndpointWithPoliciesAsync(HttpContext httpContext, IEndpointSelectorPolicy[] policies, CandidateSet candidateSet)
at Microsoft.AspNetCore.Routing.EndpointRoutingMiddleware.g__AwaitMatch|10_1(EndpointRoutingMiddleware middleware, HttpContext httpContext, Task matchTask)
at Microsoft.AspNetCore.Localization.RequestLocalizationMiddleware.Invoke(HttpContext context)
at Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddlewareImpl.Invoke(HttpContext context)

.NET Version

8.0.100

Anything else?

dotnet --info
.NET SDK:
Version: 8.0.100
Commit: 57efcf1350
Workload version: 8.0.100-manifests.8d38d0cc

Runtime Environment:
OS Name: Windows
OS Version: 10.0.22621
OS Platform: Windows
RID: win-x64
Base Path: C:\Program Files\dotnet\sdk\8.0.100\

.NET workloads installed:
Workload version: 8.0.100-manifests.8d38d0cc
[maui]
Installation Source: SDK 8.0.100
Manifest Version: 8.0.3/8.0.100
Manifest Path: C:\Program Files\dotnet\sdk-manifests\8.0.100\microsoft.net.sdk.maui\8.0.3\WorkloadManifest.json
Install Type: Msi

[android]
Installation Source: VS 17.8.34309.116
Manifest Version: 34.0.43/8.0.100
Manifest Path: C:\Program Files\dotnet\sdk-manifests\8.0.100\microsoft.net.sdk.android\34.0.43\WorkloadManifest.json
Install Type: Msi

[maui-windows]
Installation Source: VS 17.8.34309.116
Manifest Version: 8.0.3/8.0.100
Manifest Path: C:\Program Files\dotnet\sdk-manifests\8.0.100\microsoft.net.sdk.maui\8.0.3\WorkloadManifest.json
Install Type: Msi

[wasm-tools-net6]
Installation Source: VS 17.8.34309.116
Manifest Version: 8.0.0/8.0.100
Manifest Path: C:\Program Files\dotnet\sdk-manifests\8.0.100\microsoft.net.workload.mono.toolchain.net6\8.0.0\WorkloadManifest.json
Install Type: Msi

[maccatalyst]
Installation Source: VS 17.8.34309.116
Manifest Version: 17.0.8478/8.0.100
Manifest Path: C:\Program Files\dotnet\sdk-manifests\8.0.100\microsoft.net.sdk.maccatalyst\17.0.8478\WorkloadManifest.json
Install Type: Msi

[ios]
Installation Source: VS 17.8.34309.116
Manifest Version: 17.0.8478/8.0.100
Manifest Path: C:\Program Files\dotnet\sdk-manifests\8.0.100\microsoft.net.sdk.ios\17.0.8478\WorkloadManifest.json
Install Type: Msi

Host:
Version: 8.0.0
Architecture: x64
Commit: 5535e31a71

.NET SDKs installed:
6.0.414 [C:\Program Files\dotnet\sdk]
8.0.100 [C:\Program Files\dotnet\sdk]

.NET runtimes installed:
Microsoft.AspNetCore.App 6.0.22 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 6.0.25 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 7.0.14 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 8.0.0 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.NETCore.App 6.0.22 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 6.0.25 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 7.0.14 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 8.0.0 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.WindowsDesktop.App 6.0.22 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
Microsoft.WindowsDesktop.App 6.0.25 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
Microsoft.WindowsDesktop.App 7.0.14 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
Microsoft.WindowsDesktop.App 8.0.0 [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

[ralfbalzer]

I am having the same issue. My current BlazorHubs are configured as follows:

_app.MapBlazorHub("/bookingengine/_blazor"); _app.MapBlazorHub("/propertymanagement/_blazor"); _app.MapFallbackToPage("~/bookingengine/{*clientroutes:nonfile}", "/_HostBe"); _app.MapFallbackToPage("~/propertymanagement/{*clientroutes:nonfile}", "/_HostHv");

After upgrading to Version 8, I am getting "multiple endpoints match" error.

[softwaretirol]

We have the same problem

[ralfbalzer]

I am having the same issue. My current BlazorHubs are configured as follows:

_app.MapBlazorHub("/bookingengine/_blazor"); _app.MapBlazorHub("/propertymanagement/_blazor"); _app.MapFallbackToPage("~/bookingengine/{*clientroutes:nonfile}", "/_HostBe"); _app.MapFallbackToPage("~/propertymanagement/{*clientroutes:nonfile}", "/_HostHv");

After upgrading to Version 8, I am getting "multiple endpoints match" error.

I actually managed to work aournd this. The main reason why I had two Blazor Apps in Version 7 was, that there was no way to apply a different layout (at least I couldn't find one). As I needed a different layout for each of the apps, I created two.

The changes made in Version 8 have made it now possible, to create a page for each of my Apps and use the @layout directive, to apply the layout I need.

[ElliottBrand]

I'm also having this issue. My setup looks similar to this:

endpoints.MapBlazorHub();
endpoints.MapBlazorHub("/admin/_blazor");
endpoints.MapFallbackToPage("/_Host");
endpoints.MapFallbackToAreaPage("/admin/{*clientroutes:nonfile}", "/_AdminHost", "Admin");

• The admin area is in an "Area" and a custom policy scheme is added in the Startup to allow the admin area to use IdentityConstants.ApplicationScheme (along with the typical "/Identity" path). Then, the policy scheme is returning IdentityServerJwtConstants.IdentityServerJwtBearerScheme for the main app (every path other than /Identity and /Admin).
• The main app determines if the user is logged in within _Host.cshtml and provides the necessary HTML to render WebAssembly for logged in users (essentially renders <div id="app">...</div> so the WebAssembly app will load), otherwise renders the ServerPrerendered Blazor server app for non-logged-in users.

[ElliottBrand]

This is what ended up working for me. I removed both the extra MapFallbackToAreaPage (or MapFallbackToPage for some cases) and the extra MapBlazorHub from the app.UseEndpoints() section, then added the following just above the app.UseEndpoints() section:

app.Map("/admin", builder =>
{
    // This helped with my static files not being referenced at the correct path.
    builder.Use(next => context =>
    {
        // Set endpoint to null so the static files middleware will handle the request.
        context.SetEndpoint(null);

        return next(context);
    });

    builder.UsePathBase("/admin/");
    builder.UseRouting();
    builder.UseEndpoints(endpoints =>
    {
        endpoints.MapBlazorHub();
        endpoints.MapFallbackToAreaPage("/_AdminHost", "Admin");
    });
});

Reference:

• https://learn.microsoft.com/en-us/aspnet/core/blazor/host-and-deploy/?view=aspnetcore-8.0&tabs=visual-studio#server-side-blazor