Azure App Service hosted on .net 8 preview Linux does not start up, apparently asking for 8.0.0-rc to install

Question

Finally App Service can run on .NET 8 Preview under Linux container (Windows is not supported yet). I created one and deployed a simple app, but container does not start, saying the following:

2023-09-17T20:25:27.314076959Z The following frameworks were found:
2023-09-17T20:25:27.314080459Z   8.0.0-preview.7.23375.6 at [/usr/share/dotnet/shared/Microsoft.NETCore.App]
2023-09-17T20:25:27.314084859Z
2023-09-17T20:25:27.314088060Z Learn more:
2023-09-17T20:25:27.314103160Z https://aka.ms/dotnet/app-launch-failed
2023-09-17T20:25:27.314106760Z
2023-09-17T20:25:27.314110060Z To install missing framework, download:
2023-09-17T20:25:27.314113460Z https://aka.ms/dotnet-core-applaunch?framework=Microsoft.NETCore.App&framework_version=8.0.0-rc.1.23419.4&arch=x64&rid=linux-x64&os=debian.12
2023-09-17T20:25:28.143Z ERROR - Container mytestsite_0_6514069e for site mytestsite has exited, failing site start
2023-09-17T20:25:28.165Z ERROR - Container mytestsite_0_6514069e didn't respond to HTTP pings on port: 8080, failing site start. See container logs for debugging.
2023-09-17T20:25:28.168Z INFO  - Stopping site mytestsite because it failed during startup.

Similar stuff in app logs (though all shown in green, "Ok"):

2023-09-17T20:05:29.1782264 Trying to find the startup DLL name...
2023-09-17T20:05:29.1785581 Found the startup D name: Test.Api.dll
2023-09-17T20:05:29.1786987 Running the command: dotnet "Test.Api.dll"
2023-09-17T20:05:29.2267788 You must install or update .NET to run this application.
2023-09-17T20:05:29.2268172 App: /home/site/wwwroot/Test.Api.dll
2023-09-17T20:05:29.226821 Architecture: x64
2023-09-17T20:05:29.227199 Framework: 'Microsoft.NETCore.App', version '8.0.0-rc.1.23419.4' (x64)
2023-09-17T20:05:29.227326 .NET location: /usr/share/dotnet/

I replaced reference to rc packages by preview packages like 8.0.0-preview.7.23375.9 in my app, but it did not help, same error.

I wonder if I can manually install that 8.0.0-rc.1.23419.4 to the Linux machine, and also why could it ask for it as there is no direct dependency declared in the Visual Studio project file. There is a file created during the publish process called Test.Api.runtimeconfig.json and it points to 8.0.0-rc, but I'm not sure how it's created and managed, inside the file:

      {
        "name": "Microsoft.AspNetCore.App",
        "version": "8.0.0-rc.1.23421.29"
      }

I think there 2 ways to fix it: 1) install 8.0.0-rc to the Linux box manually or 2) update github yml script somehow to instruct it to install that specific ver of .net to the Linux box before the build action

Answer 1

When I tried to deploy my sample .NET 8 web app to Linux Azure App Service(.NET8) through visual studio, I was facing the same issue.

Try below steps to fix this error:

• Open your project in Visual Studio, Right click on the Project solution=> Publish.
• Create publish profile to deploy the project to Azure by selecting your .NET8 Linux Azure app service.
• Before publishing the profile, click on Show all settings:

Change Deployment Mode from Framework-dependent to Self-Contained:

Publish the profile:

Response: