Blazor app with RCL and UseStaticFiles will not server blazor.web.js in .NET 10

[TimPurdum]

Version Used: .NET 10

Steps to Reproduce:

1. Create a new project with the ".NET MAUI Blazor Hybrid and WebApp" template and selecting Interactive Auto render mode.
2. In the .Web app Program.cs, replace MapStaticAssets with UseStaticFiles.
3. In App.razor, replace the assets dictionary entry for blazor.web.js with a simple script tag: <script src="_framework/blazor.web.js"></script>.

Expected Behavior:
Assets, including the blazor bootstrap file, should be served as they were in .NET 9. As is documented in ASP.NET Core Blazor static files and Static files in ASP.NET Core, there are valid reasons to use this setup.

Actual Behavior:
Error Failed to load resource: the server responded with a status of 404 () in the browser when loading https://localhost:XXXX/_framework/blazor.web.js, and thus no interactivity (counter button).

[TimPurdum]

It does look like the pattern described here Large Collection of Assets is the new solution to this, using <StaticWebAssetEndpointExclusionPattern> to identify the assets you want to not fingerprint/compress, and then using UseStaticFiles and MapStaticAssets together. However, I could not find anyplace in the docs that asserted that UseStaticFiles by itself was insufficient for Blazor, and indeed there are multiple places where it is implied to still work.

[javiercn]

@TimPurdum thanks for contacting us.

Could you try with <RequiresAspNetWebAssets>true</RequiresAspNetWebAssets> in the host project (the one that references the web.sdk)

[batkuip]

<RequiresAspNetWebAssets>true</RequiresAspNetWebAssets>

This worked for me. I was having a similar problem following https://learn.microsoft.com/en-us/aspnet/core/blazor/components/integration?view=aspnetcore-10.0#configuration - also resulting in 404.

[bdovaz]

@TimPurdum thanks for contacting us.

Could you try with <RequiresAspNetWebAssets>true</RequiresAspNetWebAssets> in the host project (the one that references the web.sdk)

@javiercn Can you explain why when updating a Blazor Server project (I don't know if the server part is relevant) from .NET 9 to .NET 10, I got the error mentioned, and why that property fixed it? Thank you.

[TimPurdum]

@javiercn I put that in the of the .Web (Server) project. Does not solve the problem as far as I can tell. I had actually already tried that based on the other gissues.

[javiercn]

@TimPurdum thanks for contacting us.
Could you try with <RequiresAspNetWebAssets>true</RequiresAspNetWebAssets> in the host project (the one that references the web.sdk)

@javiercn Can you explain why when updating a Blazor Server project (I don't know if the server part is relevant) from .NET 9 to .NET 10, I got the error mentioned, and why that property fixed it? Thank you.

I don't know your specific details. But in 10.0, we stopped embedding the server.js and the .web.js files inside their respective assemblies so that we can compress and fingerprint them like any other files.

We use the presence of a .razor file to detect that the app uses Blazor and bring the files only in that case. It needs to be done this way because the files get brought in by an automatically imported package that is only added during restore. We can't just add the package because we don't want to bring it on for other scenarios like minimal APIs.

[javiercn]

@javiercn I put that in the of the .Web (Server) project. Does not solve the problem as far as I can tell. I had actually already tried that based on the other gissues.

We'll take a look to see what's going on.