Docker container not working for blazor server app after upgrade to pre7

Docker container not working for blazor server app after upgrade to pre7

After upgrading an existing blazor server app to preview7 from preview6, the docker container version does not run and fails with the following error message. The container is created, but run in debug failed with this message:

It was not possible to find any compatible framework version
The specified framework 'Microsoft.AspNetCore.App', version '3.0.0-preview7.19365.7' was not found.
  - The following frameworks were found:
      3.0.0-preview6.19307.2 at [/usr/share/dotnet/shared/Microsoft.AspNetCore.App]

When running docker version in release mode, I see in the console log that still preview6 files are loaded:

[...]
Microsoft.Hosting.Lifetime: Information: Now listening on: https://

Microsoft.Hosting.Lifetime: Information: Now listening on: http://

      Application started. Press Ctrl+C to shut down.
Microsoft.Hosting.Lifetime: Information: Application started. Press Ctrl+C to shut down.

      Hosting environment: Development
Microsoft.Hosting.Lifetime: Information: Hosting environment: Development

      Content root path: /app
Microsoft.Hosting.Lifetime: Information: Content root path: /app
"/usr/share/dotnet/shared/Microsoft.NETCore.App/3.0.0-preview6-27804-01/System.Net.Security.dll" wurde geladen. Das Laden von Symbolen wurde übersprungen. Das Modul ist optimiert, und die Debugoption "Nur eigenen Code" ist aktiviert.
"/usr/share/dotnet/shared/Microsoft.NETCore.App/3.0.0-preview6-27804-01/System.Collections.NonGeneric.dll" wurde geladen. Das Laden von Symbolen wurde übersprungen. Das Modul ist optimiert, und die Debugoption "Nur eigenen Code" ist aktiviert.
"/usr/share/dotnet/shared/Microsoft.NETCore.App/3.0.0-preview6-27804-01/System.Runtime.Intrinsics.dll" wurde geladen. Das Laden von Symbolen wurde übersprungen. Das Modul ist optimiert, und die Debugoption "Nur eigenen Code" ist aktiviert.
info: Microsoft.AspNetCore.Hosting.Diagnostics[1]
      Request starting HTTP/2 GET https://localhost:44356/  
Microsoft.AspNetCore.Hosting.Diagnostics: Information: Request starting HTTP/2 GET https://localhost:44356/  
"/usr/share/dotnet/shared/Microsoft.NETCore.App/3.0.0-preview6-27804-01/System.Security.Principal.dll" wurde geladen. Das Laden von Symbolen wurde übersprungen. Das Modul ist optimiert, und die Debugoption "Nur eigenen Code" ist aktiviert.
"/usr/share/dotnet/shared/Microsoft.NETCore.App/3.0.0-preview6-27804-01/System.ComponentModel.Annotations.dll" wurde geladen. Das Laden von Symbolen wurde übersprungen. Das Modul ist optimiert, und die Debugoption "Nur eigenen Code" ist aktiviert.
[...]

latest Visual Studio Preview .net SDK has been installed and dependencies have been upgraded to preview7 nuget packages. App is running fine as .net core and IIS, but not with docker from visual studio. Worked with preview6 without any problem.

Here is my local dotnet --info:

.NET Core SDK (reflecting any global.json):
 Version:   3.0.100-preview7-012821
 Commit:    6348f1068a

Runtime Environment:
 OS Name:     Windows
 OS Version:  10.0.17763
 OS Platform: Windows
 RID:         win10-x64
 Base Path:   C:\Program Files\dotnet\sdk\3.0.100-preview7-012821\

Host (useful for support):
  Version: 3.0.0-preview7-27912-14
  Commit:  4da6ee6450

.NET Core SDKs installed:
  2.1.503 [C:\Program Files\dotnet\sdk]
  2.1.602 [C:\Program Files\dotnet\sdk]
  2.1.604 [C:\Program Files\dotnet\sdk]
  2.1.700 [C:\Program Files\dotnet\sdk]
  2.1.800-preview-009696 [C:\Program Files\dotnet\sdk]
  2.1.800 [C:\Program Files\dotnet\sdk]
  2.2.300 [C:\Program Files\dotnet\sdk]
  2.2.400-preview-010219 [C:\Program Files\dotnet\sdk]
  2.2.400 [C:\Program Files\dotnet\sdk]
  3.0.100-preview7-012821 [C:\Program Files\dotnet\sdk]

.NET Core runtimes installed:
  Microsoft.AspNetCore.All 2.1.7 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.All 2.1.9 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.All 2.1.11 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.All 2.1.12 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.All 2.2.5 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.All 2.2.6 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.App 2.1.7 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 2.1.9 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 2.1.11 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 2.1.12 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 2.2.5 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 2.2.6 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 3.0.0-preview7.19365.7 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.NETCore.App 2.1.7 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.1.9 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.1.11 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.1.12 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.2.5 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.2.6 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 3.0.0-preview7-27912-14 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.WindowsDesktop.App 3.0.0-preview7-27912-14 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]

To install additional .NET Core runtimes or SDKs:
  https://aka.ms/dotnet-download

How to reproduce

The same happens with a fresh project from an included template:

• Using the balzor server app template
• add docker support in visual studio
• run the app via docker from visual studio

###dockkerfile for template from balzor server project

FROM mcr.microsoft.com/dotnet/core/aspnet:3.0-buster-slim AS base
WORKDIR /app
EXPOSE 80
EXPOSE 443

FROM mcr.microsoft.com/dotnet/core/sdk:3.0-buster AS build
WORKDIR /src
COPY ["WebApplication3test/WebApplication3test.csproj", "WebApplication3test/"]
RUN dotnet restore "WebApplication3test/WebApplication3test.csproj"
COPY . .
WORKDIR "/src/WebApplication3test"
RUN dotnet build "WebApplication3test.csproj" -c Release -o /app

FROM build AS publish
RUN dotnet publish "WebApplication3test.csproj" -c Release -o /app

FROM base AS final
WORKDIR /app
COPY --from=publish /app .
ENTRYPOINT ["dotnet", "WebApplication3test.dll"]

[whentotrade]

I was able to solve the error by updating the created dockerfile manully to pull the correct images:

Changed: FROM mcr.microsoft.com/dotnet/core/aspnet:3.0-buster-slim AS base

To: FROM mcr.microsoft.com/dotnet/core/aspnet:3.0.0-preview7-buster-slim AS base

and

Changed: FROM mcr.microsoft.com/dotnet/core/sdk:3.0-buster AS build

To: FROM mcr.microsoft.com/dotnet/core/sdk:3.0.100-preview7-buster AS build

Not sure why I needed to change these tags in the dockerfile from the template but afterwars the error is gone.

[mikesisti]

@Kavinci’s solution fixed the problem for me.