在我的例子中，我只是关闭了app form模拟器 然后再运行一次

react-native运行android

你还没有启动捆扎机呢。在项目的根目录下运行npm start或react-native start，然后再执行react-native Run -android。

对我来说，这个问题始于升级react-native。为了添加64位支持，必须进行升级。

Before:
-------- 
Environment:
Node: 10.15.0
npm: 6.9.0
Watchman: 4.9.0
Xcode: Not Found
Android Studio: 3.4 AI-183.6156.11.34.5692245

Packages: (wanted => installed)
react: 16.0.0-alpha.12 => 16.0.0-alpha.12
react-native: ~0.55.2 => 0.55.4
react-native-cli: 2.0.1

After:
------
info 
React Native Environment Info:
Binaries:
Node: 10.15.0
npm: 6.9.0
Watchman: 4.9.0
SDKs:
Android SDK:
API Levels: 23, 26, 27, 28
Build Tools: 27.0.3, 28.0.3
System Images: android-28 | Google APIs Intel x86 Atom
IDEs:
Android Studio: 3.4 AI-183.6156.11.34.5692245
Xcode: /undefined - /usr/bin/xcodebuild
npmPackages:
react: ^16.8.6 => 16.9.0 
react-native: 0.59.9 => 0.59.9 
npmGlobalPackages:
create-react-native-app: 2.0.2
react-native-cli: 2.0.1

另外，我为升级做了一个重要的改变是在../android/build/build.gradle中

android {
    ...
    defaultConfig {
        ...
        targetSdkVersion 28
        ...
    }
    ...
}

当我试图将构建(.apk)上传到goole play控制台时，我不得不将targetSdkVersion从27更改为28。 我没有意识到这是导致我上述错误的根本原因。@tom和@tinmarfrutos的立即回答是完全有道理的。

我通过添加android:usesCleartextTraffic="true"到我的android/app/src/debug/AndroidManifest.xml解决了这个问题

在我的例子中，我只是关闭了app form模拟器 然后再运行一次

react-native运行android

    this works for me on ubuntu
    
    1. if you are having node version 17 first downgrade its version:-
    You can use n for node's version management.
    
    this is very easy to use.
    $ npm install -g n
    
    then you can show your node version:
    $ node -v
    v16.13.2
    
    2. create an assets folder inside root of the project:-
    project\android\app\src\main\assets
    set folder name should be assets

3. now the final step implement the given code inside the project folder:- 

$cd project 
/project$ react-native bundle --platform android --dev false --entry-file index.js --bundle-output android/app/src/main/assets/index.android.bundle --assets-dest android/app/src/main/res

4. after following all these step react-native was successfully running on my pc

这种错误的可能性也是错误的路径，检查一次

 export ANDROID_HOME=/Users/microrentindia/Library/Android/sdk/
 export PATH=$PATH:$ANDROID_HOME/tools:$ANDROID_HOME/platform-tools