Module build failed: Error: emitFile is required from module system at Object.module.exports

When I import element-ui, it occure this problem. ERROR in .//element-ui/lib/theme-chalk/fonts/element-icons.woff Module build failed: Error: emitFile is required from module system at Object.module.exports (D:\jsSpace\rent-house\vue2-happyfri\node_modules\file-loader\index.js:9:27) at Object.loader (D:\jsSpace\rent-house\vue2-happyfri\node_modules\\url-loader\dist\index.js:76:19) @ .//css-loader!./~/element-ui/lib/theme-chalk/index.css 6:811-848

ERROR in .//element-ui/lib/theme-chalk/fonts/element-icons.ttf Module build failed: Error: emitFile is required from module system at Object.module.exports (D:\jsSpace\rent-house\vue2-happyfri\node_modules\file-loader\index.js:9:27) at Object.loader (D:\jsSpace\rent-house\vue2-happyfri\node_modules\\url-loader\dist\index.js:76:19) @ .//css-loader!./~/element-ui/lib/theme-chalk/index.css 6:879-915