Sending "devMenu" to all React Native apps failed. Make sure your app is running in the simulator or on a phone connected via USB. info Opening developer menu..
warn No apps connected. Sending "reload" to all React Native apps failed. Make sure your app is running in the simulator or on a phone connected via USB. info Reloading app... warn No apps connected. Sending "devMenu" to all React Native apps failed. Make sure your app is running in the simulator or on a phone connected via USB. info Opening developer menu... N
1.我这个问题出现的原因一开始是因为的node安装的是12.19.1版本，然后经过确认需要安装12.9.1版本，所以我node重新安装了.
2.重新安装之后还是这个错误，然后我突然想起来我rn全局那个 React Native CLI是用12.19.1安装的，可能有问题，于是重新卸载和安装
npm uninstall react-native-cli npm install -g react-native-cli //因为我安装教程安装的是全局的，所以要卸载掉重新安装，包括npm包
3.然后就搞定了，进入这个界面
原文：https://www.cnblogs.com/shuen/p/14874206.html