安装小提琴也给我带来了类似的问题。卸载fiddler并从机器中删除fiddler代理。config(来自Framework和Framework64)解决了这个问题。

你需要在Nuget中添加代理设置。配置文件。有关详细信息，请参阅此链接:Nuget配置部分和Nuget代理设置。

我必须在命令提示符中从.sln所在的文件夹中运行dotnet还原，这是成功的(而VS还原nuget包失败)。在此之后，我至少可以在Visual Studio下列出已安装的包，但“更新”仍然无法加载。

I had the same error message while scaffolding Identity to my ASP.NET Core MVC project. Since my connection was not behind a proxy, removing/editing proxy configurations didn't make sense. And I didn't want to delete a file or uninstall PMC either. While looking around I realized a "Clear All Nuget Cache(s)" button on Tools --> Options --> NuGet Package Manager --> General. After pressing the button I had to wait for some time for the operation to complete. After that I tried to scaffold the Identity again but it didn't work. Then I decided to restart VS and voila :)

我有这个错误，然后我意识到我是用我的个人微软帐户而不是我的工作帐户登录的。

希望这能有所帮助。

当我试图在本地托管的Gitlab实例中设置NuGet包时遇到了这个错误。错误提示401未经授权的代码。解决方案是用以下方法去除有害源:

nuget source Remove -Name SOURCE_NAME

然后添加相同的源，但这次在命令中指定用户名和密码:

nuget source Add -Name SOURCE_NAME -Source SOURCE_URL -UserName GITLAB_DEPLOY_TOKEN_USERNAME -Password GITLAB_DEPLOY_TOKEN