离线构建 .NET Core 应用程序不会创建“NuGetFallbackFolder”文件夹

Question

I had installed VS2019 and running "dotnet --version" command shows "3.1.100".

When i try to build a .NET standard library project without connecting to the network the following error is thrown

"error NU1100: Unable to resolve 'NETStandard.Library (>= 2.0.3)' for '.NETStandard,Version=v2.0'

My project has the following tag

<TargetFramework>netstandard2.0</TargetFramework>

Earlier i was using Binaries of "dotnet-sdk-2.1.301-win-x64" and when i build the project, the restore command was automatically extracting and creating the "NuGetFallbackFolder" folder when i was building without connecting to the network.

The same doesn't happen after installing VS2019.

IS there a workaround for this?

Answer 1

Copied from github:

Starting in VS 16.3 and .NET Core 3.0, we no longer use a nuget fallback folder. A side-effect of this is that in order for you to be able to work with .NET Standard 2.0 offline, you need to restore a .net standard 2.0 project at least once while online. And every time if you clean your NuGet cache

Answer 2

.NET Standard 2.0 projects can be compiled on .NET Core 3.1.100 SDK successfully. Ensure that you are not having global.json with older SDK defined.

Because based on that error you have, the inability to restore ".NET Standard 2.0.3" means that somewhere in your codes you have global.json or you are explicitly referencing .NET runtime version in the csproj, instead of just using TFM of netstandard2.0 as main target defined in the csproj file.