无法加载资金localhost：8081 / index.bundle

Question

我是REACT-NATIVE的新手，因为昨天开始，react-native cli的运行状况不佳。首先，由于某些路径问题，它不能执行“ react-native run-is”。然后今天早上固定。人们修复它后，在模拟器中运行该应用程序出现了问题。它有错误，无法加载bundle（http://localhost:8081/index.bundle?..。）我尝试了其他帖子中的以下建议。

1. 运行npm install
2. 删除node_module并运行npm install
3. 将端口号更改为其他名称。

"dependencies": {
    "react": "16.8.3",
    "react-native": "0.59.1"   },   
"devDependencies": {
    "@babel/core": "^7.4.0",
    "@babel/runtime": "^7.4.2",
    "@react-native-community/eslint-config": "^0.0.3",
    "babel-jest": "^24.5.0",
    "eslint": "^5.15.3",
    "jest": "^24.5.0",
    "metro-react-native-babel-preset": "^0.53.1",
    "react-test-renderer": "16.8.3"   },   
"jest": {
    "preset": "react-native"   }

"dependencies": { "react": "16.8.3", "react-native": "0.59.1" }, "devDependencies": { "@babel/core": "^7.4.0", "@babel/runtime": "^7.4.2", "@react-native-community/eslint-config": "^0.0.3", "babel-jest": "^24.5.0", "eslint": "^5.15.3", "jest": "^24.5.0", "metro-react-native-babel-preset": "^0.53.1", "react-test-renderer": "16.8.3" }, "jest": { "preset": "react-native" }