在我的情况下，我的android物理设备没有连接到运行在我的开发机器上的js服务器。所以我必须手动设置调试服务器主机和端口在我的android设备。

对我来说，我不得不为react native打开多个node js终端，并且在运行应用程序到我的android设备之前忘记关闭。 我关闭终端，再次运行，它成功加载页面

当你试图在不关闭节点服务器的情况下运行前一个应用程序时，有时会发生这种情况，所以尝试重新启动React。要做到这一点，只需运行以下命令:

1. To kill current processes
killall node -9 

2. To Start React  Native
react-native start 

3. Then Run android
react-native run-android

I've never seen this error before, but whenever I can't get Xcode and React-Native to play well together, I do a couple of things. Check what version of Xcode I'm working with. If it needs to be updated, I update it. Then clearing watchman and the cache are the second place I go. I don't use the reset cache command. It always says that I need to verify the cache, so I skip that (you can do it though, I just get confused). I use rm -rf $TMPDIR/react-* to get rid of any cached builds. If that doesn't work, I try to build the app in Xcode, then work my way from there, to build it with react-native run-ios. With this error message, it seems you might start by trying to build it with Xcode. Hope that helps...let me know your progress with it. Good luck! (Also, you could update to RN 0.51 as another attempt to get your versions synced.)

我更新了app.json中的SDK版本，以匹配包中的react原生SDK版本。Json来修复这个问题

在app.json

"sdkVersion": "37.0.0",

在package.json

"react-native": "https://github.com/expo/react-native/archive/sdk-37.0.1.tar.gz",

我可以通过删除node_modules并再次运行npm install来修复这个问题