将Netstandard程序包安装到.NET Core

Question

The library Google.Apis on NuGet claims the following:

Supported Platforms:

• .NET Framework 4.5+
• NetStandard1.3, providing .NET Core support

However, the command dotnet add package Google.Apis tells me error: Package 'Google.Apis' is incompatible with 'all' frameworks in project '/home/pavel/[...]/api.csproj'. .

Here is the csproj file being used:

<Project Sdk="Microsoft.NET.Sdk.Web">

  <PropertyGroup>
    <TargetFramework>netcoreapp2.2</TargetFramework>
  </PropertyGroup>

  <ItemGroup>
    <Folder Include="wwwroot\" />
    <Folder Include="Utils\" />
  </ItemGroup>

  <ItemGroup>
    <PackageReference Include="Microsoft.AspNetCore.All" />
  </ItemGroup>
</Project>

How do I install the package?

Answer 1

As discussed in the comments to the question, this was caused due to a nuget.config file that removed all sources. When I reproduced the scenario on my local machine, here's the full output:

  Writing /tmp/tmpd4dcSu.tmp
info : Adding PackageReference for package 'Google.Apis' into project '/home/zivkan/apiTest/apiTest.csproj'.
log  : Restoring packages for /home/zivkan/apiTest/apiTest.csproj...
error: Unable to resolve 'Google.Apis ' for '.NETCoreApp,Version=v2.1'.
error: Package 'Google.Apis' is incompatible with 'all' frameworks in project '/home/zivkan/apiTest/apiTest.csproj'.

The second error message, the one you reported in your question, is very misleading. However, the first error message "Unable to resolve" gives a good hint that NuGet is unable to find the package.