PublishSingleFile results in 404 errors for Nuget components

[Webreaper]

Developing a Blazor app in VS for Mac 8.4 Preview (8.4 build 2414) and publishing a single-file executable for Linux, the JS and CSS components for NuGet packages result in a 404 when executing the app. This worked fine when I did it about 2 weeks ago, so looks to be a regression in the latest preview version of 16.4 which installed within the last week.

To reproduce:

1. Write a blazor app referencing a component such as Blazored.TypeAhead or Blazored.Modal
2. Publish the app as a single-file EXE targetting ubuntu (I haven't tried other targets):
   dotnet publish Damselfly.Web -r ubuntu.18.04-x64 -c Release /p:PublishSingleFile=true
3. Copy the single-file EXE onto a linux server, and execute.
4. The app fails to render properly, and opening the console in Chrome gives, for example:

GET http://server:6363/_content/Blazored.Typeahead/blazored-typeahead.css net::ERR_ABORTED 404 (Not Found)
search:12 GET http://server:6363/_content/Blazor.ContextMenu/blazorContextMenu.min.css net::ERR_ABORTED 404 (Not Found)
search:11 GET http://server:6363/_content/Blazored.Modal/blazored-modal.css net::ERR_ABORTED 404 (Not Found)
search:356 GET http://server:6363/_content/Blazor.ContextMenu/blazorContextMenu.min.js net::ERR_ABORTED 404 (Not Found)
search:357 GET http://server:6363/_content/Blazored.Typeahead/blazored-typeahead.js net::ERR_ABORTED 404 (Not Found)

5. Re-publish the app without PublishSingleFile=true, and then copy across to the server, app runs fine.

ASP.Net Core version: I tried this with DotNet Core 3.1 preview, and just in case it was a regression with that version I also tried with DotNet Core 3.0. Same problem with both. So it looks like it's a regression with the single-file packaging for Blazor apps not including the _content folder properly.

Output of dotnet --info:

.NET Core SDK (reflecting any global.json):
 Version:   3.1.100-preview2-014569
 Commit:    4bd5d24d87

Runtime Environment:
 OS Name:     Mac OS X
 OS Version:  10.14
 OS Platform: Darwin
 RID:         osx.10.14-x64
 Base Path:   /usr/local/share/dotnet/sdk/3.1.100-preview2-014569/

Host (useful for support):
  Version: 3.1.0-preview2.19525.6
  Commit:  5672978d91

.NET Core SDKs installed:
  2.0.0 [/usr/local/share/dotnet/sdk]
  2.1.4 [/usr/local/share/dotnet/sdk]
  2.1.301 [/usr/local/share/dotnet/sdk]
  2.1.302 [/usr/local/share/dotnet/sdk]
  2.1.500 [/usr/local/share/dotnet/sdk]
  2.1.505 [/usr/local/share/dotnet/sdk]
  2.1.701 [/usr/local/share/dotnet/sdk]
  3.0.100-preview7-012821 [/usr/local/share/dotnet/sdk]
  3.0.100-preview9-014004 [/usr/local/share/dotnet/sdk]
  3.0.100 [/usr/local/share/dotnet/sdk]
  3.1.100-preview2-014569 [/usr/local/share/dotnet/sdk]

.NET Core runtimes installed:
  Microsoft.AspNetCore.All 2.1.1 [/usr/local/share/dotnet/shared/Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.All 2.1.2 [/usr/local/share/dotnet/shared/Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.All 2.1.6 [/usr/local/share/dotnet/shared/Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.All 2.1.9 [/usr/local/share/dotnet/shared/Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.All 2.1.12 [/usr/local/share/dotnet/shared/Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.App 2.1.1 [/usr/local/share/dotnet/shared/Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 2.1.2 [/usr/local/share/dotnet/shared/Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 2.1.6 [/usr/local/share/dotnet/shared/Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 2.1.9 [/usr/local/share/dotnet/shared/Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 2.1.12 [/usr/local/share/dotnet/shared/Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 3.0.0-preview7.19365.7 [/usr/local/share/dotnet/shared/Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 3.0.0-preview9.19424.4 [/usr/local/share/dotnet/shared/Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 3.0.0 [/usr/local/share/dotnet/shared/Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 3.1.0-preview2.19528.8 [/usr/local/share/dotnet/shared/Microsoft.AspNetCore.App]
  Microsoft.NETCore.App 2.0.0 [/usr/local/share/dotnet/shared/Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.0.5 [/usr/local/share/dotnet/shared/Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.1.1 [/usr/local/share/dotnet/shared/Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.1.2 [/usr/local/share/dotnet/shared/Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.1.6 [/usr/local/share/dotnet/shared/Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.1.9 [/usr/local/share/dotnet/shared/Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.1.12 [/usr/local/share/dotnet/shared/Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.1.13 [/usr/local/share/dotnet/shared/Microsoft.NETCore.App]
  Microsoft.NETCore.App 3.0.0-preview7-27912-14 [/usr/local/share/dotnet/shared/Microsoft.NETCore.App]
  Microsoft.NETCore.App 3.0.0-preview9-19423-09 [/usr/local/share/dotnet/shared/Microsoft.NETCore.App]
  Microsoft.NETCore.App 3.0.0 [/usr/local/share/dotnet/shared/Microsoft.NETCore.App]
  Microsoft.NETCore.App 3.1.0-preview2.19525.6 [/usr/local/share/dotnet/shared/Microsoft.NETCore.App]

[javiercn]

@Webreaper thanks for contacting us.

This can be a bug, we might not be adding ExcludeFromSingleFile to the static web assets.

[Webreaper]

Updated to 8.4 build 2535 last night, and the problem is still present (I know you're still probably investigating so wasn't expecting it to be fixed :))

[Webreaper]

Any update on this? I've just updated to DotNetCore SDK v3.1.0 and the problem still happens.

[javiercn]

@Webreaper this is scheduled for preview5, so I wouldn't expect any action on this until the end of the year.

You can probably workaround this through MSBuild extensibility by setting the ExcludeFromSingleFile property on the ResolvedFileToPublish items for the static web assets.

[Webreaper]

Thanks for the update. I'm using normal publishing for now, but thanks for the tip!

[mkArtakMSFT]

Removed the servicing-consider label from the issue, as we track it on the PRs.