我最近开始使用现有项目，当尝试从https://nuget.episerver.com在Package Manager控制台中安装软件包时，会发生以下情况（与显示的软件包相同的问题也会发生。）
PM> Install-Package EPiServer.Social -Version 2.1.2.8000
Attempting to resolve dependency 'EPiServer.Packaging (≥ 3.2.0 && < 4.0)'.
Attempting to resolve dependency 'EPiServer.Framework (≥ 8.0.0 && < 9.0)'.
Attempting to resolve dependency 'Newtonsoft.Json (≥ 5.0.8 && < 7.0)'.
Attempting to resolve dependency 'Microsoft.AspNet.Mvc (≥ 4.0.20710.0 && < 6.0)'.
Attempting to resolve dependency 'Microsoft.AspNet.WebPages (≥ 2.0.20710.0 && < 2.1)'.
Attempting to resolve dependency 'Microsoft.Web.Infrastructure (≥ 1.0.0.0)'.
Attempting to resolve dependency 'Microsoft.AspNet.Razor (≥ 2.0.20710.0 && < 2.1)'.
Attempting to resolve dependency 'structuremap (≥ 2.6.4.1 && < 3.0)'.
Attempting to resolve dependency 'Nuget.Core (≥ 2.5 && < 2.8)'.
Attempting to resolve dependency 'EPiServer.CMS.Core (≥ 8.0 && < 9.0)'.
Attempting to resolve dependency 'EPiServer.Logging.Log4Net (≥ 1.0 && < 2.0)'.
Attempting to resolve dependency 'log4net (= 1.2.10)'.
Attempting to resolve dependency 'Castle.Windsor (≥ 3.2 && < 4.0)'.
Attempting to resolve dependency 'Castle.Core (≥ 3.2.0)'.
Attempting to resolve dependency 'EPiServer.CMS.UI (≥ 8.0 && < 9.0)'.
Attempting to resolve dependency 'EPiServer.CMS.UI.Core (= 8.0.2)'.
Attempting to resolve dependency 'DotNetZip (= 1.9.1.8)'.
Installing 'EPiServer.Social 2.1.2.8000'.
Successfully installed 'EPiServer.Social 2.1.2.8000'.
Install failed. Rolling back...
Install-Package : Updating 'EPiServer.Framework 8.2.0' to 'EPiServer.Framework 7.15.0' failed. Unable to find versions of 'EPiServer.CMS.Core, EPiServer.Logging.Log4Net, EPiServer.Commerce.Core' that are compatible with 'EPiServer.Framework 7.15.0'.
At line:1 char:1
+ Install-Package EPiServer.Social -Version 2.1.2.8000
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ CategoryInfo : NotSpecified: (:) [Install-Package], InvalidOperationException
+ FullyQualifiedErrorId : NuGetCmdletUnhandledException,NuGet.PowerShell.Commands.InstallPackageCommand
成功安装和安装失败之间存在小的中断。
EPiServer在某些时候已经从7.15.0升级到8.2.0。
这可能是什么原因？