.NET Maui无法在Visual Studio for Mac Preview 17.4部署到Android模拟器

问题概述 #

使用.NET Maui开发跨平台业务应用，此前运行正常。将.NET Core SDK从6.0.400-preview.22330.6升级至6.0.400后，出现部署异常：调试时构建成功，但Visual Studio for Mac在「部署到设备」环节后提示错误：Cannot execute 'Users/xxxx/src/Mobile/bin/Debug/net6.0-android/Mobile.dll'。

「部署到设备」窗口无错误、无警告，多数目标因输出文件已最新被跳过。通过命令行和VS for Mac清理项目均无效，但使用命令dotnet build -t:Run -f:net6.0-android可在模拟器正常运行应用。

查看VS for Mac日志发现核心错误：加载obj/Debug/net6.0-android/android/AndroidManifest.xml时触发ArgumentNullException（参数versions为空），即使该文件实际存在。新建测试项目仍出现相同问题。

解决方法 #

1. 更新Visual Studio for Mac到最新版本 #

该问题是VS for Mac与.NET 6.0.400 SDK的兼容性Bug，更新到17.3.6及以上版本可修复Manifest加载时的空参数问题。

2. 临时绕过VS for Mac部署，使用命令行调试 #

若暂时无法更新VS，可通过以下命令继续开发：

• 启动模拟器调试：dotnet build -t:Run -f:net6.0-android
• 部署到真机：dotnet build -t:Install -f:net6.0-android，完成后通过VS或adb启动应用调试。

3. 手动指定Android SDK版本（可选） #

在项目.csproj文件中明确指定Android SDK相关版本，避免工具链自动检测异常：

<PropertyGroup>
  <TargetFramework>net6.0-android</TargetFramework>
  <AndroidSdkVersion>31</AndroidSdkVersion>
  <AndroidTargetSdkVersion>31</AndroidTargetSdkVersion>
  <AndroidMinSdkVersion>21</AndroidMinSdkVersion>
</PropertyGroup>

问题根源 #

异常源于VS for Mac的MonoDroid工具链在加载自动生成的AndroidManifest时，未正确初始化AndroidVersions参数，导致空指针异常。命令行工具链不受影响，因其Manifest加载逻辑与VS for Mac内部实现不同。

相关错误日志 #

ERROR [2022-08-15 15:48:19Z]: Error loading android manifest '/Users/xxxx/src/Mobile/obj/Debug/net6.0-android/android/AndroidManifest.xml'
System.ArgumentNullException: Value cannot be null. (Parameter 'versions')
   at Xamarin.Android.Tools.AndroidAppManifest.Load(String filename, AndroidVersions versions) in /Users/runner/work/1/s/MonoDevelop.MonoDroid/external/androidtools/external/xamarin-android-tools/src/Xamarin.Android.Tools.AndroidSdk/AndroidAppManifest.cs:line 84
   at MonoDevelop.MonoDroid.ProjectSystem.AndroidApplicationManifest..ctor(String manifestFile, AndroidProjectProperties projectProperties) in /Users/runner/work/1/s/MonoDevelop.MonoDroid/MonoDevelop.MonoDroid/ProjectSystem/PropertiesProviders/AndroidApplicationManifest.cs:line 13
   at MonoDevelop.MonoDroid.ProjectSystem.AndroidManifestCache.CreateNewManifest(String filename) in /Users/runner/work/1/s/MonoDevelop.MonoDroid/MonoDevelop.MonoDroid/ProjectSystem/PropertiesProviders/AndroidManifestCache.cs:line 33

INFO [2022-08-15 15:48:19Z]: Add-in loaded: DotNetCore.Debugger
INFO [2022-08-15 15:48:19Z]: Add-in loaded: MonoDevelop.Debugger.Soft.AspNet
ERROR [2022-08-15 15:48:19Z]: Cannot execute "/Users/xxxx/src/Mobile/bin/Debug/net6.0-android/Mobile.dll"

不同位置的AndroidManifest内容 #

1. obj/Debug/net6.0-android下自动生成的Manifest #

<?xml version="1.0" encoding="utf-8"?>
<!--
    This code was generated by a tool.
    It was generated from /Users/xxxx/src/NewTest/Platforms/Android/AndroidManifest.xml
    Changes to this file may cause incorrect behavior and will be lost if
    the contents are regenerated.
    -->
<manifest xmlns:android="http://schemas.android.com/apk/res/android" android:versionCode="1" package="com.companyname.newtest" android:versionName="1.0">
  <uses-sdk android:minSdkVersion="21" android:targetSdkVersion="31" />
  <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
  <uses-permission android:name="android.permission.INTERNET" />
  <application android:allowBackup="true" android:icon="@mipmap/appicon" android:roundIcon="@mipmap/appicon_round" android:supportsRtl="true" android:name="crc64035c0982af6367fe.MainApplication" android:label="NewTest" android:debuggable="true" android:extractNativeLibs="true">
    <activity android:configChanges="density|orientation|smallestScreenSize|screenLayout|screenSize|uiMode" android:theme="@style/Maui.SplashTheme" android:name="crc64035c0982af6367fe.MainActivity" android:exported="true">
      <intent-filter>
        <action android:name="android.intent.action.MAIN" />
        <category android:name="android.intent.category.LAUNCHER" />
      </intent-filter>
    </activity>
    <activity android:configChanges="orientation|screenSize" android:exported="true" android:name="crc6468b6408a11370c2f.WebAuthenticatorIntermediateActivity" />
    <provider android:authorities="com.companyname.newtest.fileProvider" android:exported="false" android:grantUriPermissions="true" android:name="microsoft.maui.essentials.fileProvider">
      <meta-data android:name="android.support.FILE_PROVIDER_PATHS" android:resource="@xml/microsoft_maui_essentials_fileprovider_file_paths" />
    </provider>
    <receiver android:enabled="true" android:exported="false" android:label="Essentials Connectivity Broadcast Receiver" android:name="crc64e53d2f592022988e.ConnectivityBroadcastReceiver" />
    <activity android:configChanges="orientation|screenSize" android:exported="true" android:name="crc64ba438d8f48cf7e75.IntermediateActivity" />
    <receiver android:enabled="true" android:exported="false" android:label="Essentials Battery Broadcast Receiver" android:name="crc640a8d9a12ddbf2cf2.BatteryBroadcastReceiver" />
    <receiver android:enabled="true" android:exported="false" android:label="Essentials Energy Saver Broadcast Receiver" android:name="crc640a8d9a12ddbf2cf2.EnergySaverBroadcastReceiver" />
    <service android:name="crc64396a3fe5f8138e3f.KeepAliveService" />
    <provider android:name="mono.MonoRuntimeProvider" android:exported="false" android:initOrder="1999999999" android:authorities="com.companyname.newtest.mono.MonoRuntimeProvider.__mono_init__" />
  </application>
</manifest>

2. Platforms/Android目录下的原始Manifest #

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android">
    <application android:allowBackup="true" android:icon="@mipmap/appicon" android:roundIcon="@mipmap/appicon_round" android:supportsRtl="true"></application>
    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
    <uses-permission android:name="android.permission.INTERNET" />
</manifest>

3. Bin文件夹签名包中提取的Manifest #

<?xml version="1.0" encoding="utf-8" standalone="no"?><manifest xmlns:android="http://schemas.android.com/apk/res/android" android:compileSdkVersion="31" android:compileSdkVersionCodename="12" package="com.companyname.newtest" platformBuildVersionCode="31" platformBuildVersionName="12">
    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>
    <uses-permission android:name="android.permission.INTERNET"/>
    <application android:allowBackup="true" android:appComponentFactory="androidx.core.app.CoreComponentFactory" android:debuggable="true" android:extractNativeLibs="true" android:icon="@mipmap/appicon" android:label="NewTest" android:name="crc64035c0982af6367fe.MainApplication" android:roundIcon="@mipmap/appicon_round" android:supportsRtl="true">
        <activity android:configChanges="density|orientation|screenLayout|screenSize|smallestScreenSize|uiMode" android:exported="true" android:name="crc64035c0982af6367fe.MainActivity" android:theme="@style/Maui.SplashTheme">
            <intent-filter>
                <action android:name="android.intent.action.MAIN"/>
                <category android:name="android.intent.category.LAUNCHER"/>
            </intent-filter>
        </activity>
        <activity android:configChanges="orientation|screenSize" android:exported="true" android:name="crc6468b6408a11370c2f.WebAuthenticatorIntermediateActivity"/>
        <provider android:authorities="com.companyname.newtest.fileProvider" android:exported="false" android:grantUriPermissions="true" android:name="microsoft.maui.essentials.fileProvider">
            <meta-data android:name="android.support.FILE_PROVIDER_PATHS" android:resource="@xml/microsoft_maui_essentials_fileprovider_file_paths"/>
        </provider>
        <receiver android:enabled="true" android:exported="false" android:label="Essentials Connectivity Broadcast Receiver" android:name="crc64e53d2f592022988e.ConnectivityBroadcastReceiver"/>
        <activity android:configChanges="orientation|screenSize" android:exported="true" android:name="crc64ba438d8f48cf7e75.IntermediateActivity"/>
        <receiver android:enabled="true" android:exported="false" android:label="Essentials Battery Broadcast Receiver" android:name="crc640a8d9a12ddbf2cf2.BatteryBroadcastReceiver"/>
        <receiver android:enabled="true" android:exported="false" android:label="Essentials Energy Saver Broadcast Receiver" android:name="crc640a8d9a12ddbf2cf2.EnergySaverBroadcastReceiver"/>
        <service android:name="crc64396a3fe5f8138e3f.KeepAliveService"/>
        <provider android:authorities="com.companyname.newtest.mono.MonoRuntimeProvider.__mono_init__" android:exported="false" android:initOrder="1999999999" android:name="mono.MonoRuntimeProvider"/>
        <provider android:authorities="com.companyname.newtest.androidx-startup" android:exported="false" android:name="androidx.startup.InitializationProvider">
            <meta-data android:name="androidx.emoji2.text.EmojiCompatInitializer" android:value="androidx.startup"/>
            <meta-data android:name="androidx.lifecycle.ProcessLifecycleInitializer" android:value="androidx.startup"/>
        </provider>
        <uses-library android:name="androidx.window.extensions" android:required="false"/>
        <uses-library android:name="androidx.window.sidecar" android:required="false"/>
    </application>
</manifest>

内容的提问来源于stack exchange，提问作者user19771002