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.)

这对我来说很管用:

react-native start --reset-cache

我已经尝试了上面的解决方案，但将此添加到AndroidManifest.xml似乎可以修复它。

  android:usesCleartextTraffic="true"

在我的例子中，我手动更改了expo版本。我得到了同样的问题，因为我忘记更新app.json中的sdkVersion和package.json中的babel-preset-expo

然后运行:expo r -c清除缓存并启动应用程序。