我发现这很奇怪，但我有一个解决办法。 我注意到每隔一段时间我的项目文件夹变成只读，我不能从VS.中保存它，所以我读了一个建议，将NPM从本地用户PATH转移到系统范围的PATH全局变量，它就像一个咒语。

在设备上运行

我找到了另一个答案。

adb reverse:仅适用于Android 5.0+ (API 21)。 另一种方法:通过摇动设备打开开发人员菜单，进入开发设置，进入设备调试服务器主机，输入您的机器的IP地址和本地开发服务器的端口

当你的服务器运行(react-native start)时，将JS文件捆绑到你的apk中下载到你的应用程序的assets目录:

curl "http://localhost:8081/index.android.bundle?platform=android" -o "android/app/src/main/assets/index.android.bundle"

在下一个版本(0.12)中，我们将修复react-native bundle命令，以与预期的android项目一起工作。

从项目目录中运行

react-native start

输出如下:

$ react-native start
 ┌────────────────────────────────────────────────────────────────────────────┐ 
 │  Running packager on port 8081.                                            │ 
 │                                                                            │ 
 │  Keep this packager running while developing on any JS projects. Feel      │ 
 │  free to close this tab and run your own packager instance if you          │ 
 │  prefer.                                                                   │ 
 │                                                                            │ 
 │  https://github.com/facebook/react-native                                  │ 
 │                                                                            │ 
 └────────────────────────────────────────────────────────────────────────────┘ 
Looking for JS files in
   /home/user/AwesomeProject 


React packager ready.

[11:30:10 PM] <START> Building Dependency Graph
[11:30:10 PM] <START> Crawling File System
[11:30:16 PM] <END>   Crawling File System (5869ms)
[11:30:16 PM] <START> Building in-memory fs for JavaScript
[11:30:17 PM] <END>   Building in-memory fs for JavaScript (852ms)
[11:30:17 PM] <START> Building in-memory fs for Assets
[11:30:17 PM] <END>   Building in-memory fs for Assets (838ms)
[11:30:17 PM] <START> Building Haste Map
[11:30:18 PM] <START> Building (deprecated) Asset Map
[11:30:18 PM] <END>   Building (deprecated) Asset Map (220ms)
[11:30:18 PM] <END>   Building Haste Map (759ms)
[11:30:18 PM] <END>   Building Dependency Graph (8319ms)

此错误可以通过以下步骤轻松解决:

    //run the command at /android sdk / platforms-tool folder
        adb reverse tcp:8081 tcp:8081

    //now come to root folder of your app
    1. npm start
    2. create 'assets' folder inside rootApp/android/app/src/main/
    3. curl "http://localhost:8081/index.android.bundle?platform=android" -o "android/app/src/main/assets/index.android.bundle"
    4. make sure anyone physical or virtual device attached is running.
    5. react-native run-android

从react-native目录运行npm start对我来说很有效。