我一直在使用 Xamarin 开发一个 android 应用程序。直到今天我更新 Xamarin 和 Android-SDK 时，它一直运行良好，突然我收到以下错误消息：
“初始化任务 PropertyGroup 时出错：未注册任务 PropertyGroup。”
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<AssemblyName>InspectAdminClientAndroid</AssemblyName>
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<DefineConstants>DEBUG;</DefineConstants>
<ErrorReport>prompt</ErrorReport>
<WarningLevel>4</WarningLevel>
<ConsolePause>false</ConsolePause>
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<OutputPath>bin\Release</OutputPath>
<ErrorReport>prompt</ErrorReport>
<WarningLevel>4</WarningLevel>
<ConsolePause>false</ConsolePause>
<AndroidUseSharedRuntime>false</AndroidUseSharedRuntime>
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<Reference Include="System.Xml" />
<Reference Include="System.Core" />
<Reference Include="Mono.Android" />
<Reference Include="Newtonsoft.Json">
<HintPath>..\..\Downloads\Json50r6\Bin\Portable40\Newtonsoft.Json.dll</HintPath>
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<Compile Include="Activities\CustomerAliasActivity.cs" />
<Compile Include="Activities\LoadSettingsActivity.cs" />
<Compile Include="Activities\LoadingObjectsActivity.cs" />
<Compile Include="Activities\ObjectListActivity.cs" />
<Compile Include="Activities\ObjectDetailsActivity.cs" />
<Compile Include="Activities\LoadingInspectionsActivity.cs" />
<Compile Include="Activities\InspectionListActivity.cs" />
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<AndroidResource Include="Resources\drawable\slidingmenu_shadows.xml" />
<AndroidResource Include="Resources\drawable\upgrade_button_background.xml" />
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<AndroidResource Include="Resources\drawable-hdpi\ic_coordinate.png" />
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