npm ERR! code ERESOLVEnpm ERR! ERESOLVE could not resolvenpm ERR!

npm ERR! code ERESOLVE
npm ERR! ERESOLVE could not resolve
npm ERR!
npm ERR! While resolving: [email protected]
npm ERR! Found: [email protected]
npm ERR! node_modules/webpack
npm ERR!   webpack@"^4.0.0" from @vue/[email protected]
npm ERR!   node_modules/@vue/cli-plugin-babel
npm ERR!     dev @vue/cli-plugin-babel@"^3.3.0" from the root project
npm ERR!   webpack@"^4.0.0" from @vue/[email protected]
npm ERR!   node_modules/@vue/cli-plugin-eslint
npm ERR!     dev @vue/cli-plugin-eslint@"^3.3.0" from the root project
npm ERR!   4 more (@vue/cli-service, compression-webpack-plugin, ...)
npm ERR!
npm ERR! Could not resolve dependency:
npm ERR! vue-loader@"^15.7.0" from the root project
npm ERR!
npm ERR! Conflicting peer dependency: [email protected]
npm ERR! node_modules/webpack
npm ERR!   peer webpack@"^5.0.0" from [email protected]
npm ERR!   node_modules/css-loader
npm ERR!     peer css-loader@"*" from [email protected]
npm ERR!     node_modules/vue-loader
npm ERR!       vue-loader@"^15.7.0" from the root project
npm ERR!
npm ERR! Fix the upstream dependency conflict, or retry
npm ERR! this command with --force, or --legacy-peer-deps
npm ERR! to accept an incorrect (and potentially broken) dependency resolution.
npm ERR!

解决方案

npm install --save-dev html-webpack-plugin --legacy-peer-deps

npm install xxxx --legacy-peer-deps命令是什么？为什么可以解决下载时候产生的依赖冲突呢？
npm install xxxx --legacy-peer-deps命令与其说是告诉npm要去干什么，不如说是告诉npm不要去干什么。

legacy的意思：遗产/（软件或硬件）已过时但因使用范围广而难以替代的；而npm install xxxx --legacy-peer-deps命令用于绕过peerDependency里依赖的自动安装；它告诉npm忽略项目中引入的各个依赖模块之间依赖相同但版本不同的问题，以npm v3-v6的方式去继续执行安装操作。