Visual studio 2017 为什么我的Visual Studio 2017中没有提供Dot Net Framework 4.5.2？

我最近升级到VS2017并卸载了VS2015。 但是，当我在VS2015 Framework 4.5.2中打开我的旧项目时，它不会显示为一个选项

当我尝试安装Framework 4.5.2时，我收到以下消息

与声明无需采取任何行动的链接

我正在运行Windows 7 Ultimate N service Pack 1

[更新]

在尝试删除和恢复framework 4.5.2之后，我尝试修复。 修复尝试以消息结束

Setup operation failed

这是日志

The product failed to install the listed workloads and components due to one or more package failures.

Incomplete workloads
    Visual Studio core editor (Microsoft.VisualStudio.Workload.CoreEditor,version=15.0.26228.0)

Incomplete components
    Visual Studio core editor (Microsoft.VisualStudio.Component.CoreEditor,version=15.0.26208.0)

You can search for solutions using the information below, modify your selections for the above workloads and components and retry the installation, or remove the product from your machine.

Following is a collection of individual package failures that led to the incomplete workloads and components above. To search for existing reports of these specific problems, please copy and paste the URL from each package failure into a web browser. If the issue has already been reported, you can find solutions or workarounds there. If the issue has not been reported, you can create a new issue where other people will be able to find solutions or workarounds.

Package 'Microsoft.Net.4.6.FullRedist,version=4.6.81.6' failed to repair.
    Search URL: https://aka.ms/VSSetupErrorReports?q=PackageId=Microsoft.Net.4.6.FullRedist;PackageAction=Repair;ReturnCode=5100
    Impacted workloads
        Visual Studio core editor (Microsoft.VisualStudio.Workload.CoreEditor,version=15.0.26228.0)
    Impacted components
        Visual Studio core editor (Microsoft.VisualStudio.Component.CoreEditor,version=15.0.26208.0)
    Log
        C:\Users\kirstenAdmin\AppData\Local\Temp\dd_setup_20170711130222_002_Microsoft.Net.4.6.FullRedist.log
    Details
        Command executed: "C:\ProgramData\Microsoft\VisualStudio\Packages\Microsoft.Net.4.6.FullRedist,version=4.6.81.6\dotNetFx-x86-x64-AllOS-ENU.exe" /q /norestart /repair /KeepAUPaused /ChainingPackage Visual_Studio_15_Setup /CEIPconsent /log "C:\Users\kirstenAdmin\AppData\Local\Temp\dd_setup_20170711130222_002_Microsoft.Net.4.6.FullRedist.log"
        Return code: 5100
        Return code details: Asia

我不知道它是否相关，但我确实在不久前使用了以下安装程序来摆脱VS2015

我刚刚注意到VS2015正在程序和功能中显示，所以我尝试取消安装VS2015。我想出了一个方法，但我认为我从未安装过“辅助安装程序”

进入“Visual Studio 2017安装程序”（它应该是开始菜单中的快捷方式）并单击“修改”。在顶部，选择“单个组件”。确保选中“.NET Framework 4.5.2目标包”。如果不是，请选择它，然后单击右下角的“修改”。

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完全卸载VS2015和VS2017，然后重新安装VS2017，只会解决此问题

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我原以为我以前未安装VS2015，但程序和功能中仍保留了一个卸载程序，所以我使用了它。

谢谢，但它已被选中。我将尝试取消检查，然后修改，然后重新检查。可能尝试取消选择，让它卸载，然后重新添加。安装程序的第一个屏幕上还有一个“修复”选项（在启动右侧的3行下）。如果删除和重新添加目标包不起作用，我会试一试。我现在尝试启动时出现“未知错误”，在重新安装4.5.2之后，我已经开始修复。修复进行得如何？