我的项目新建流程如下

运行之后就是如下报错 

解决办法：

安装如下依赖： 

 npm i postcss-loader autoprefixer@8.0.0

 npm run build 编译失败

 安装如下依赖：

npm install postcss@8.2.2

最终package.json文件如下

{"name": "lsyj-app-vuecli","version": "1.1.0","private": true,"scripts": {"serve": "npm run dev:h5","build": "npm run build:h5","build:app-plus": "cross-env NODE_ENV=production UNI_PLATFORM=app-plus vue-cli-service uni-build","build:custom": "cross-env NODE_ENV=production uniapp-cli custom","build:h5": "cross-env NODE_ENV=production UNI_PLATFORM=h5 vue-cli-service uni-build","build:mp-360": "cross-env NODE_ENV=production UNI_PLATFORM=mp-360 vue-cli-service uni-build","build:mp-alipay": "cross-env NODE_ENV=production UNI_PLATFORM=mp-alipay vue-cli-service uni-build","build:mp-baidu": "cross-env NODE_ENV=production UNI_PLATFORM=mp-baidu vue-cli-service uni-build","build:mp-jd": "cross-env NODE_ENV=production UNI_PLATFORM=mp-jd vue-cli-service uni-build","build:mp-kuaishou": "cross-env NODE_ENV=production UNI_PLATFORM=mp-kuaishou vue-cli-service uni-build","build:mp-lark": "cross-env NODE_ENV=production UNI_PLATFORM=mp-lark vue-cli-service uni-build","build:mp-qq": "cross-env NODE_ENV=production UNI_PLATFORM=mp-qq vue-cli-service uni-build","build:mp-toutiao": "cross-env NODE_ENV=production UNI_PLATFORM=mp-toutiao vue-cli-service uni-build","build:mp-weixin": "cross-env NODE_ENV=production UNI_PLATFORM=mp-weixin vue-cli-service uni-build","build:mp-xhs": "cross-env NODE_ENV=production UNI_PLATFORM=mp-xhs vue-cli-service uni-build","build:quickapp-native": "cross-env NODE_ENV=production UNI_PLATFORM=quickapp-native vue-cli-service uni-build","build:quickapp-webview": "cross-env NODE_ENV=production UNI_PLATFORM=quickapp-webview vue-cli-service uni-build","build:quickapp-webview-huawei": "cross-env NODE_ENV=production UNI_PLATFORM=quickapp-webview-huawei vue-cli-service uni-build","build:quickapp-webview-union": "cross-env NODE_ENV=production UNI_PLATFORM=quickapp-webview-union vue-cli-service uni-build","dev:app-plus": "cross-env NODE_ENV=development UNI_PLATFORM=app-plus vue-cli-service uni-build --watch","dev:custom": "cross-env NODE_ENV=development uniapp-cli custom","dev:h5": "cross-env NODE_ENV=development UNI_PLATFORM=h5 vue-cli-service uni-serve","dev:mp-360": "cross-env NODE_ENV=development UNI_PLATFORM=mp-360 vue-cli-service uni-build --watch","dev:mp-alipay": "cross-env NODE_ENV=development UNI_PLATFORM=mp-alipay vue-cli-service uni-build --watch","dev:mp-baidu": "cross-env NODE_ENV=development UNI_PLATFORM=mp-baidu vue-cli-service uni-build --watch","dev:mp-jd": "cross-env NODE_ENV=development UNI_PLATFORM=mp-jd vue-cli-service uni-build --watch","dev:mp-kuaishou": "cross-env NODE_ENV=development UNI_PLATFORM=mp-kuaishou vue-cli-service uni-build --watch","dev:mp-lark": "cross-env NODE_ENV=development UNI_PLATFORM=mp-lark vue-cli-service uni-build --watch","dev:mp-qq": "cross-env NODE_ENV=development UNI_PLATFORM=mp-qq vue-cli-service uni-build --watch","dev:mp-toutiao": "cross-env NODE_ENV=development UNI_PLATFORM=mp-toutiao vue-cli-service uni-build --watch","dev:mp-weixin": "cross-env NODE_ENV=development UNI_PLATFORM=mp-weixin vue-cli-service uni-build --watch","dev:mp-xhs": "cross-env NODE_ENV=development UNI_PLATFORM=mp-xhs vue-cli-service uni-build --watch","dev:quickapp-native": "cross-env NODE_ENV=development UNI_PLATFORM=quickapp-native vue-cli-service uni-build --watch","dev:quickapp-webview": "cross-env NODE_ENV=development UNI_PLATFORM=quickapp-webview vue-cli-service uni-build --watch","dev:quickapp-webview-huawei": "cross-env NODE_ENV=development UNI_PLATFORM=quickapp-webview-huawei vue-cli-service uni-build --watch","dev:quickapp-webview-union": "cross-env NODE_ENV=development UNI_PLATFORM=quickapp-webview-union vue-cli-service uni-build --watch","info": "node node_modules/@dcloudio/vue-cli-plugin-uni/commands/info.js","serve:quickapp-native": "node node_modules/@dcloudio/uni-quickapp-native/bin/serve.js","test:android": "cross-env UNI_PLATFORM=app-plus UNI_OS_NAME=android jest -i","test:h5": "cross-env UNI_PLATFORM=h5 jest -i","test:ios": "cross-env UNI_PLATFORM=app-plus UNI_OS_NAME=ios jest -i","test:mp-baidu": "cross-env UNI_PLATFORM=mp-baidu jest -i","test:mp-weixin": "cross-env UNI_PLATFORM=mp-weixin jest -i"},"dependencies": {"@dcloudio/uni-app": "^2.0.2-3090520231028001","@dcloudio/uni-app-plus": "^2.0.2-3090520231028001","@dcloudio/uni-h5": "^2.0.2-3090520231028001","@dcloudio/uni-i18n": "^2.0.2-3090520231028001","@dcloudio/uni-mp-360": "^2.0.2-3090520231028001","@dcloudio/uni-mp-alipay": "^2.0.2-3090520231028001","@dcloudio/uni-mp-baidu": "^2.0.2-3090520231028001","@dcloudio/uni-mp-jd": "^2.0.2-3090520231028001","@dcloudio/uni-mp-kuaishou": "^2.0.2-3090520231028001","@dcloudio/uni-mp-lark": "^2.0.2-3090520231028001","@dcloudio/uni-mp-qq": "^2.0.2-3090520231028001","@dcloudio/uni-mp-toutiao": "^2.0.2-3090520231028001","@dcloudio/uni-mp-vue": "^2.0.2-3090520231028001","@dcloudio/uni-mp-weixin": "^2.0.2-3090520231028001","@dcloudio/uni-mp-xhs": "^2.0.2-3090520231028001","@dcloudio/uni-quickapp-native": "^2.0.2-3090520231028001","@dcloudio/uni-quickapp-webview": "^2.0.2-3090520231028001","@dcloudio/uni-stacktracey": "^2.0.2-3090520231028001","@dcloudio/uni-stat": "^2.0.2-3090520231028001","@vue/shared": "^3.0.0","autoprefixer": "^8.0.0","core-js": "^3.8.3","flyio": "^0.6.2","postcss": "^8.2.2","postcss-loader": "^7.3.3","vue": ">= 2.6.14 < 2.7","vuex": "^3.2.0"},"devDependencies": {"@dcloudio/types": "^3.3.2","@dcloudio/uni-automator": "^2.0.2-3090520231028001","@dcloudio/uni-cli-i18n": "^2.0.2-3090520231028001","@dcloudio/uni-cli-shared": "^2.0.2-3090520231028001","@dcloudio/uni-helper-json": "*","@dcloudio/uni-migration": "^2.0.2-3090520231028001","@dcloudio/uni-template-compiler": "^2.0.2-3090520231028001","@dcloudio/vue-cli-plugin-hbuilderx": "^2.0.2-3090520231028001","@dcloudio/vue-cli-plugin-uni": "^2.0.2-3090520231028001","@dcloudio/vue-cli-plugin-uni-optimize": "^2.0.2-3090520231028001","@dcloudio/webpack-uni-mp-loader": "^2.0.2-3090520231028001","@dcloudio/webpack-uni-pages-loader": "^2.0.2-3090520231028001","@vue/cli-plugin-babel": "~5.0.0","@vue/cli-service": "~5.0.0","babel-plugin-import": "^1.11.0","cross-env": "^7.0.2","jest": "^25.4.0","node-sass": "^4.14.1","postcss-comment": "^2.0.0","sass-loader": "^7.3.1","vue-template-compiler": ">= 2.6.14 < 2.7"},"browserslist": ["Android >= 4.4","ios >= 9"],"uni-app": {"scripts": {}}
}