我目前正在构建一个 react-native 应用程序，每次运行时都会收到此错误消息：react-native run-android
错误信息：
info Running jetifier to migrate libraries to AndroidX. You can disable it using "--no-jetifier" flag.
Jetifier found 1052 file(s) to forward-jetify. Using 8 workers...
info Starting JS server...
info Launching emulator...
error Failed to launch emulator. Reason: Emulator exited before boot..
warn Please launch an emulator manually or connect a device. Otherwise app may fail to launch.
info Installing the app...
> Configure project :react-native-firebase_app
:react-native-firebase_app package.json found at /Users/asakoulas/BODYBOX/Bodybox/node_modules/@react-native-firebase/app/package.json
:react-native-firebase_app:firebase.bom using default value: 28.1.0
:react-native-firebase_app:play.play-services-auth using default value: 19.0.0
:react-native-firebase_app package.json found at /Users/asakoulas/BODYBOX/Bodybox/node_modules/@react-native-firebase/app/package.json
:react-native-firebase_app:version set from package.json: 12.1.0 (12,1,0 - 12001000)
:react-native-firebase_app:android.compileSdk using custom value: 29
:react-native-firebase_app:android.targetSdk using custom value: 29
:react-native-firebase_app:android.minSdk using custom value: 21
:react-native-firebase_app:reactNativeAndroidDir /Users/myuser/appname/appname/node_modules/react-native/android
Mapping new ns http://schemas.android.com/repository/android/common/02 to old ns http://schemas.android.com/repository/android/common/01
Mapping new ns http://schemas.android.com/repository/android/generic/02 to old ns http://schemas.android.com/repository/android/generic/01
Mapping new ns http://schemas.android.com/sdk/android/repo/addon2/02 to old ns http://schemas.android.com/sdk/android/repo/addon2/01
Mapping new ns http://schemas.android.com/sdk/android/repo/repository2/02 to old ns http://schemas.android.com/sdk/android/repo/repository2/01
Mapping new ns http://schemas.android.com/sdk/android/repo/sys-img2/02 to old ns http://schemas.android.com/sdk/android/repo/sys-img2/01
Mapping new ns http://schemas.android.com/repository/android/common/02 to old ns http://schemas.android.com/repository/android/common/01
Mapping new ns http://schemas.android.com/repository/android/generic/02 to old ns http://schemas.android.com/repository/android/generic/01
Mapping new ns http://schemas.android.com/sdk/android/repo/addon2/02 to old ns http://schemas.android.com/sdk/android/repo/addon2/01
Mapping new ns http://schemas.android.com/sdk/android/repo/repository2/02 to old ns http://schemas.android.com/sdk/android/repo/repository2/01
Mapping new ns http://schemas.android.com/sdk/android/repo/sys-img2/02 to old ns http://schemas.android.com/sdk/android/repo/sys-img2/01
Checking the license for package Android SDK Build-Tools 30.0.2 in /Users/username/Library/Android/sdk/licenses
License for package Android SDK Build-Tools 30.0.2 accepted.
Preparing "Install Android SDK Build-Tools 30.0.2 (revision: 30.0.2)".
"Install Android SDK Build-Tools 30.0.2 (revision: 30.0.2)" ready.
Installing Android SDK Build-Tools 30.0.2 in /Users/asakoulas/Library/Android/sdk/build-tools/30.0.2
"Install Android SDK Build-Tools 30.0.2 (revision: 30.0.2)" complete.
"Install Android SDK Build-Tools 30.0.2 (revision: 30.0.2)" finished.
Mapping new ns http://schemas.android.com/repository/android/common/02 to old ns http://schemas.android.com/repository/android/common/01
Mapping new ns http://schemas.android.com/repository/android/generic/02 to old ns http://schemas.android.com/repository/android/generic/01
Mapping new ns http://schemas.android.com/sdk/android/repo/addon2/02 to old ns http://schemas.android.com/sdk/android/repo/addon2/01
Mapping new ns http://schemas.android.com/sdk/android/repo/repository2/02 to old ns http://schemas.android.com/sdk/android/repo/repository2/01
Mapping new ns http://schemas.android.com/sdk/android/repo/sys-img2/02 to old ns http://schemas.android.com/sdk/android/repo/sys-img2/01
WARNING:: The specified Android SDK Build Tools version (28.0.3) is ignored, as it is below the minimum supported version (30.0.2) for Android Gradle Plugin 4.2.2.
Android SDK Build Tools 30.0.2 will be used.
To suppress this warning, remove "buildToolsVersion '28.0.3'" from your build.gradle file, as each version of the Android Gradle Plugin now has a default version of the build tools.
WARNING:: The specified Android SDK Build Tools version (28.0.3) is ignored, as it is below the minimum supported version (30.0.2) for Android Gradle Plugin 4.2.2.
Android SDK Build Tools 30.0.2 will be used.
To suppress this warning, remove "buildToolsVersion '28.0.3'" from your build.gradle file, as each version of the Android Gradle Plugin now has a default version of the build tools.
> Task :app:installDebug FAILED
Skipping device 'emulator-5554' (emulator-5554): Device is OFFLINE.
134 actionable tasks: 2 executed, 132 up-to-date
FAILURE: Build failed with an exception.
* What went wrong:
Execution failed for task ':app:installDebug'.
> com.android.builder.testing.api.DeviceException: No online devices found.
* Try:
Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output. Run with --scan to get full insights.
* Get more help at https://help.gradle.org
BUILD FAILED in 14s
error Failed to install the app. Make sure you have the Android development environment set up: https://reactnative.dev/docs/environment-setup.
Error: Command failed: ./gradlew app:installDebug -PreactNativeDevServerPort=8081
FAILURE: Build failed with an exception.
* What went wrong:
Execution failed for task ':app:installDebug'.
> com.android.builder.testing.api.DeviceException: No online devices found.
* Try:
Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output. Run with --scan to get full insights.
* Get more help at https://help.gradle.org
BUILD FAILED in 14s
at makeError (/Users/username/Appname/app/node_modules/@react-native-community/cli-platform-android/node_modules/execa/index.js:174:9)
at /Users/username/Appname/app/node_modules/@react-native-community/cli-platform-android/node_modules/execa/index.js:278:16
at processTicksAndRejections (internal/process/task_queues.js:95:5)
at async runOnAllDevices (/Users/username/Appname/app/node_modules/@react-native-community/cli-platform-android/build/commands/runAndroid/runOnAllDevices.js:94:5)
at async Command.handleAction (/Users/username/Appname/app/node_modules/@react-native-community/cli/build/index.js:186:9)
info Run CLI with --verbose flag for more details.
在我尝试集成 Firebase 并更新 Android Studio 之前，命令 (react-native run-android) 一直运行良好。
我尝试做几件事来解决这个问题，比如重新安装 android studio 或更新 sdk 工具。
当我运行 (react-native run-android) 时，JS 服务器运行成功，android 模拟器打开但没有下载应用程序。
当我在终端中运行：adb devices 时，我得到：
List of devices attached
emulator-5554 offline
我已经尝试删除、冷重启、重启模拟器，但它没有帮助，总是显示离线。
我非常感谢您的帮助。
提前致谢！
答案 0 :(得分：0)
您能否尝试手动打开模拟器然后运行命令...如果它不起作用意味着它在您的代码中的某个地方...或者如果它不在您的代码中，您可以尝试检查这些答案之一。 .. Failed to launch emulator. Reason: Emulator exited before boot en React Native when react-native run-android
对不起，如果我帮不上忙...
答案 1 :(得分：0)
致所有正在阅读本文并遇到相同问题的人：
我最终按照 Medium.com 上的指南解决了这个问题：
结果是android studio和新mac m1芯片的模拟器出错。
**之前有人删除了答案，我不知道为什么。在删除之前，您能否至少解释一下为什么要删除它。