Xamarin Forms Android 错误：请安装包“Android 支持库”

我最近将项目上传到 Git，并使用自动生成的 Xamarin/Windows/MacOS/VisualStudio .gitignore 文件。我在 iOS 上做了很多工作和测试，但现在我回到 android，但在构建 Project.Droid 版本时，我收到以下错误：

Error   11  Please install package: 'Android Support Library' available in SDK installer. Android resource directory C:\Users\dev\AppData\Local\Xamarin\Android.Support.v4\21.0.3\embedded\./ doesn't exist.    MyProject.Droid
Error   5   Please install package: 'Android Support Library' available in SDK installer. Java library file C:\Users\dev\AppData\Local\Xamarin\Android.Support.v4\21.0.3\embedded\classes.jar doesn't exist.    MyProject.Droid
Error   8   Please install package: 'Android Support Library' available in SDK installer. Java library file C:\Users\dev\AppData\Local\Xamarin\Android.Support.v4\21.0.3\embedded\libs/internal_impl-21.0.3.jar doesn't exist.  MyProject.Droid
Error   4   Reason: C:\Users\dev\AppData\Local\Xamarin\Android.Support.v4\21.0.3\android_m2repository_r10.zip is not a valid zip file   MyProject.Droid
Error   7   Reason: C:\Users\dev\AppData\Local\Xamarin\Android.Support.v4\21.0.3\android_m2repository_r10.zip is not a valid zip file   MyProject.Droid
Error   10  Reason: C:\Users\dev\AppData\Local\Xamarin\Android.Support.v4\21.0.3\android_m2repository_r10.zip is not a valid zip file   MyProject.Droid
Error   3   Unzipping failed. Please download https://dl-ssl.google.com/android/repository/android_m2repository_r10.zip and extract it to the C:\Users\dev\AppData\Local\Xamarin\Android.Support.v4\21.0.3\content directory.   MyProject.Droid
Error   6   Unzipping failed. Please download https://dl-ssl.google.com/android/repository/android_m2repository_r10.zip and extract it to the C:\Users\dev\AppData\Local\Xamarin\Android.Support.v4\21.0.3\content directory.   MyProject.Droid
Error   9   Unzipping failed. Please download https://dl-ssl.google.com/android/repository/android_m2repository_r10.zip and extract it to the C:\Users\dev\AppData\Local\Xamarin\Android.Support.v4\21.0.3\content directory.   MyProject.Droid

有谁知道我该如何解决它？我使用管理员权限检查了我的 SDK 管理器，并且我已经安装了 Android 支持库

错误消息非常明确地告诉你

1. 错误是什么

   C:\Users\dev\AppData\Local\Xamarin\Android.Support.v4\21.0.3\android_m2repository_r10.zip 不是有效的 zip 文件

2. 如何修复它

   请下载https://dl-ssl.google.com/android/repository/android_m2repository_r10.zip https://dl-ssl.google.com/android/repository/android_m2repository_r10.zip并将其解压到 C:\Users\dev\AppData\Local\Xamarin\Android.Support.v4\21.0.3\content 目录。