I’ve never touched C# or .NET development before but was thrown into it for a hobby project two days ago, so please bear with my ignorance.

I am updating a .net project from framework version 2 to 5 using microsoft.net.sdk (ver. 8.0.300 [/snap/dotnet-sdk/245/sdk] installed via snap on Ubuntu 22.04)

I also running an azure pipeline to build my code and the agent I use is windows-2019

I can restore the project successfully, but not build.

When building I get an error requiring me to use framework Microsoft.NETCore.App version 3.1.0 even though I specify framework to be net5.0. This prompted me to think one of my packages required that framework so I went through my package list on the .nuget website, but everything looks to be compatible with net5.0.

What am I missing here – any input will be greatly appreciated.

The Error message is:

  CyroinvestPublicAPI -> D:a1sbinDebugnet5.0CyroinvestPublicAPI.dll
  Determining projects to restore...
  Restored C:UsersVssAdministratorAppDataLocalTempojp42vr4.spjWorkerExtensions.csproj (in 8.68 sec).
  WorkerExtensions -> C:UsersVssAdministratorAppDataLocalTempojp42vr4.spjbuildoutMicrosoft.Azure.Functions.Worker.Extensions.dll
##[error]C:UsersVssAdministrator.nugetpackagesmicrosoft.net.sdk.functions3.0.11buildMicrosoft.NET.Sdk.Functions.Build.targets(32,5): Error : It was not possible to find any compatible framework version
The framework 'Microsoft.NETCore.App', version '3.1.0' was not found.
  - The following frameworks were found:
      5.0.17 at [C:hostedtoolcachewindowsdotnetsharedMicrosoft.NETCore.App]

You can resolve the problem by installing the specified framework and/or SDK.

The specified framework can be found at:
  - https://aka.ms/dotnet-core-applaunch?framework=Microsoft.NETCore.App&framework_version=3.1.0&arch=x64&rid=win10-x64

and my csproj file looks like this:

<!--Project Sdk="Microsoft.NET.Sdk.Web"-->
<Project Sdk="Microsoft.NET.Sdk">
  <PropertyGroup>
    <TargetFramework>net5.0</TargetFramework>
    <AzureFunctionsVersion>v8</AzureFunctionsVersion>
    <FunctionsEnableWorkerIndexing>true</FunctionsEnableWorkerIndexing>
    <SelfContained>true</SelfContained>
    <!--TargetFramework>netcoreapp5</TargetFramework-->
    <!--AzureFunctionsVersion>v2</AzureFunctionsVersion-->
  </PropertyGroup>
  <ItemGroup>
    <PackageReference Include="Azure.Identity"/>
    <PackageReference Include="Azure.Security.KeyVault.Secrets"/> 
    <PackageReference Include="Microsoft.Azure.Functions.Worker"/>
    <PackageReference Include="Microsoft.Azure.Functions.Worker.Sdk"/> <!--.NETFramework 4.7.2-->
    <PackageReference Include="Microsoft.Azure.Functions.Worker.Extensions.Http"/>
    <PackageReference Include="Microsoft.Azure.KeyVault" Version="3.0.5"/>
    <PackageReference Include="Microsoft.Azure.Services.AppAuthentication"/>
    <PackageReference Include="Microsoft.Azure.WebJobs" Version="3.0.27"/>
    <PackageReference Include="Microsoft.Azure.WebJobs.Extensions.Http"/>
    <!--PackageReference Include="Microsoft.Azure.WebJobs.Extensions.Http"/-->
    <!--PackageReference Include="Microsoft.NET.Sdk.Functions"/-->
    <PackageReference Include="npgsql"/>
    <PackageReference Include="SendGrid" Version="9.12.0" />
    <PackageReference Include="System.IdentityModel.Tokens.Jwt" />
    <PackageReference Include="Microsoft.Azure.Cosmos" />
    <FrameworkReference Include="Microsoft.AspNetCore.App" />
  </ItemGroup>
  <ItemGroup>
    <None Update="host.json">
      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
    </None>
    <None Update="local.settings.json">
      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
      <CopyToPublishDirectory>Never</CopyToPublishDirectory>
    </None>
  </ItemGroup>
</Project> 

And finally my azure-pipelines.yaml file is:

# https://aka.ms/yaml

trigger:
- master
- update_5_x_x

pool:
  vmImage: windows-2019

steps:
- task: UseDotNet@2
  inputs:
    packageType: 'sdk'
    version: '5.0.x'
  displayName: 'Install .Net SDK 5.0.x'

- script: |
    dotnet --info
    dotnet --list-sdks
  displayName: 'Display .NET Info'

  
- task: DotNetCoreCLI@2
  displayName: 'dotnet restore'
  inputs:
    command: restore
    projects: '**/*.csproj'
    verbosityRestore: Detailed
    verbosityPack: Detailed


- task: DotNetCoreCLI@2
  displayName: 'dotnet build'
  inputs:
    projects: '**/*.csproj'
    verbosityRestore: Detailed
    verbosityPack: Detailed


- task: DotNetCoreCLI@2
  displayName: 'dotnet publish'
  inputs:
    command: publish
    publishWebProjects: false
    projects: '**/*.csproj'
    arguments: '--no-restore --configuration Release --output $(Build.ArtifactStagingDirectory)'
    verbosityRestore: Detailed
    verbosityPack: Detailed


- task: PublishBuildArtifacts@1
  displayName: 'Publish Artifact: drop'

I can restore the project successfully, but when building I get the following error requiring me to use framework Microsoft.NETCore.App even though I specify framework to be net5.0. This prompted me to think one of my packages required that framework so I went through my package list on the .nuget website, but everything looks to be compatible with net5.0.

I have tried different combinations of versions of packages to no avail.

Again: I am very likely overlooking something basic here – any input will be much appreciated!