我在使用Expo和iOS模拟器时也遇到了这个问题。对我有用的是擦除硬件中的模拟器>擦除所有内容和设置…

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.)

对于我的问题修复此更改模拟器与API级别低于28。这个问题的根源是API级别28及以上的网络变化。通过添加来解决这个问题

<application
     android:usesCleartextTraffic="true"

对androidManifest.xml

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

我们所做的修正是确保在构建之前设置ANDROID_HOME和PATH变量。

首先，运行以下两个命令，然后为设备构建应用程序。

export ANDROID_HOME=/Users/username/MyFiles/applications/androidsdk
export PATH=$PATH:$ANDROID_HOME/tools:$ANDROID_HOME/platform-tools

博览会用户-确保您的app.json sdk版本和包。Json的博览会版本是(可能相等)彼此兼容。