对于我的情况下，我在iOS上面临它，我试图重置和清除所有缓存使用以下命令，但失败了，尽管许多评论说，根本原因是有react打包器在某处意外运行，我重新启动了我的mac，问题仍然存在。

watchman watch-del-all && rm -rf node_modules/ && yarn cache clean && yarn install && yarn start --reset-cache

解决方案是，删除build文件夹@ /ios/build，然后执行react-native run-ios解决了它

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.)

这是我对它所做的:

关闭所有终端并再次运行构建。

你可能忘记从另一个项目关闭nodejs终端，而他们碰巧安装了不同的react版本。

因此，从nodejs服务器获取的代码与本机代码冲突。

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…

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

在你的android应用级别的gradle文件中，在依赖项中强制react原生版本。

compile ("com.facebook.react:react-native:0.52.0") { force = true }

为我工作