Nuget - 未将对象引用设置为对象的实例

Question

我在vs 2015中遇到了nuget包管理器的问题.像Unity这样的软件包安装没有问题.像EF这样的软件包在安装时遇到了问题.像Automapper这样的软件包有同样的问题,但是当我安装了这个软件包的另一个版本时,安装得很好.

这是输出:

System.NullReferenceException: Object reference not set to an instance of an object.


at NuGet.Protocol.Core.v3.GlobalPackagesFolderUtility.<AddPackageAsync>d__1.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter`1.GetResult()
   at NuGet.Protocol.Core.v3.DownloadResourceV3.<GetDownloadResourceResultAsync>d__4.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at NuGet.PackageManagement.PackageDownloader.<GetDownloadResourceResultAsync>d__1.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.ValidateEnd(Task task)
   at NuGet.PackageManagement.NuGetPackageManager.<ExecuteNuGetProjectActionsAsync>d__42.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at NuGet.PackageManagement.NuGetPackageManager.<ExecuteNuGetProjectActionsAsync>d__42.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at NuGet.PackageManagement.UI.UIActionEngine.<ExecuteActionsAsync>d__5.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at NuGet.PackageManagement.UI.UIActionEngine.<PerformActionAsync>d__3.MoveNext()
========== Finished ==========

Answer 1

Visual Studio 2022中仍然存在同样的问题。解决方案：

1. 导航到 C:\Users<您的用户名>\AppData\Roaming\NuGet // 请记住 AppData 是一个隐藏文件夹，因此您必须先让 Windows 显示隐藏文件和文件夹，然后才能看到它
2. 在记事本中打开 NuGet.Config（或任何可以让您编辑它的工具）
3. 在“packageSources”部分中，查找以下行：

添加键=“nuget.org”值=“https://api.nuget.org/v3/index.json”协议版本=“3”

并删除'protocolVersion =“3”'

4. 保存文件并重新启动 Visual Studio 2022

Answer 2

这是使用Visual Studio 2015中使用的新协议(版本3)nuget的常见问题.它具有多个nuget包,例如Microsoft.Owin 3.0.1.要解决这个问题,请访问:

C:\Users\<your user name>\AppData\Roaming\NuGet

编辑XML配置文件,注释协议3的行:

<!-- add key = "nuget.org" value = "https://api.nuget.org/v3/index.json" protocolVersion = "3" /-->
<add key = "nuget.org" value = "https://www.nuget.org/api/v2/" /> 

版本2的维护设置.保存并重新启动visual studio 2015.您现在应该可以毫无问题地恢复nuget包.