Failed to resolve loader: less-loader You may need to install it 的解决

控制台报错：
Failed to resolve loader: less-loader You may need to install it.
Error from chokidar (D:\): Error: EBUSY: resource busy or locked, lstat 'D:\DumpStack.log.tmp
Error from chokidar (D:\): Error: EBUSY: resource busy or locked, lstat 'D:\pagefile.sys

解决：我把项目关闭后重启运行之后输入了

npm install less-loader

然后在npm run serve时项目报错了：

Error: Rule can only have one resource source (provided resource and test +) in {...}

这个报错的原因是：package.json中webpack版本冲突问题.

解决方案：

删除webpack，重新装以前的版本。
npm uninstall webpack
npm install webpack@^4.0.0 --save-dev

安装完成之后重新运行项目，项目重新运行成功了。