Nuget软件包无法安装

Question

I am trying to install owin in a project and it fails with the below error its not real descriptive. If I create a new project it works just fine. How can I find out what is causing the error

I updated with -verbose but no extra info

Adding package 'Microsoft.AspNet.Identity.Core.2.2.1' to folder 'c:\Workspace\Ruby\pfg.producealliance.com\packages'
Install failed. Rolling back...
Package 'Microsoft.AspNet.Identity.Core.2.2.1' does not exist in project 'Ruby.Web'
Removing package 'Microsoft.AspNet.Identity.Core.2.2.1' from folder 'c:\Workspace\Ruby\pfg.producealliance.com\packages'
TF400024: The change on c:\Workspace\Ruby\pfg.producealliance.com\packages\Microsoft.AspNet.Identity.Core.2.2.1\Microsoft.AspNet.Identity.Core.2.2.1.nupkg cannot be undone because a file already exists at c:\Workspace\Ruby\pfg.producealliance.com\packages\Microsoft.AspNet.Identity.Core.2.2.1\Microsoft.AspNet.Identity.Core.2.2.1.nupkg. The file must be deleted from disk for the undo to succeed.
Install-Package : TF400024: The change on c:\Workspace\Ruby\pfg.producealliance.com\packages\Microsoft.AspNet.Identity.Core.2.2.1\Microsoft.AspNet.Identity.Core.2.2.1.nupkg cannot be undone because a file already exists at 
c:\Workspace\Ruby\pfg.producealliance.com\packages\Microsoft.AspNet.Identity.Core.2.2.1\Microsoft.AspNet.Identity.Core.2.2.1.nupkg. The file must be deleted from disk for the undo to succeed.
At line:1 char:1
+ Install-Package Microsoft.AspNet.Identity.Owin -ProjectName Ruby.Web  ...
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : NotSpecified: (:) [Install-Package], Exception
    + FullyQualifiedErrorId : NuGetCmdletUnhandledException,NuGet.PackageManagement.PowerShellCmdlets.InstallPackageCommand

Answer 1

How can I find out what is causing the error[?]

Pass the -Verbose flag to Install-Package . The output will hopefully tell you more precisely what went wrong. Perhaps a file is in use and cannot be copied or modified?

UPDATE: Thanks to the additional info provided by the OP, I think Nuget Package updates & Package.config remove issue (TF400024) answers your problem (hint: it's related to your project not being checked out from source control). Check out the project and try again.