背景
如果你使用了element-ui的el-tabs组件，并且想要单独升级element-ui至2.10.0，你会发现，使用了el-tabs组件的页面只要打开就卡死。原因是element-ui~2.10.0采用了不兼容vue~2.5.10的写法。于是我尝试系统性升级vue全家桶，这也是为系统赋予更多能力做准备。结果遇到一些报错，这里记录一下。
升级过程
当前版本
vue: 2.5.10
vue-loader: 13.5.0
vue-router: 3.0.1
vuex: 3.0.1
axios: 0.17.1
element-ui: 2.2.2
目标版本
vue: 2.6.10
vue-loader: 15.7.0
vue-router: 3.0.3
vuex: 3.1.1
axios: 0.18.1
element-ui: 2.10.0
报错1(包版本不匹配)
修改package.json中的依赖包版本号之后，npm install一波后就报错了。
Vue packages version mismatch:
- vue@2.6.10
- vue-template-compiler@2.5.10
This may cause things to work incorrectly. Make sure to use the same version for both.
If you are using vue-loader@>=10.0, simply update vue-template-compiler.
If you are using vue-loader@<10.0 or vueify, re-installing vue-loader/vueify should bump vue-template-compiler to the latest.
@ ./src/router/modules/test/index.js 22:23-67
@ ./src/router/common.js
@ ./src/router/index.js
@ ./src/main.js
@ multi (webpack)-dev-server/client?http://localhost:9532 webpack/hot/dev-server babel-polyfill ./src/main.js
分析：vue和vue-template-compiler两个包的版本不匹配，需要升级vue-template-compile。github搜索这个包搜不到，最后在npm包官网找到了。
解决方案：升级vue-template-compile: 2.6.10
报错2(vue-loader)
|
| <section>
| <el-form class="cl-add-form" :model="dataForm" :rules="rules" ref="dataForm" label-width="125px">
| <el-form-item label="法定节假日名称" prop="name">
@ ./src/views/backend/enterprise/holiday/add-public-holiday.vue 1:0-97 30:4-35:6 30:81-35:5
@ ./src/views lazy ^./.*$
@ ./src/authority/generate-routes.js
@ ./src/store/modules/user.js
@ ./src/store/index.js
@ ./src/main.js
@ multi (webpack)-dev-server/client?http://localhost:9532 webpack/hot/dev-server babel-polyfill ./src/main.js
error in ./src/views/backend/enterprise/holiday/add-special-holiday.vue?vue&type=template&id=09f84cb0&
Module parse failed: Unexpected token (2:0)
You may need an appropriate loader to handle this file type.
分析：经观察，发现可能是不识别vue文件或其中某部分，于是从vue-loader入手，也在网上查阅了一些资料，需要在webpack的plugins中加入vue-loader/lib/plugin。
解决方案：
const VueLoaderPlugin = require('vue-loader/lib/plugin')
plugins: [
new VueLoaderPlugin(),
// 其他插件
...
]
报错3(postcss-loader)
(Emitted value instead of an instance of Error)
⚠️ PostCSS Loader
Previous source map found, but options.sourceMap isn't set.
In this case the loader will discard the source map entirely for performance reasons.
See https://github.com/postcss/postcss-loader#sourcemap for more information.
@ ./node_modules/vue-style-loader!./node_modules/css-loader?{"sourceMap":false}!./node_modules/vue-loader/lib/loaders/stylePostLoader.js!./node_modules/postcss-loader/lib?{"sourceMap":false}!./node_modules/vue-loader/lib?{"loaders":{"css":["vue-style-loader",{"loader":"css-loader","options":{"sourceMap":false}}],"postcss":["vue-style-loader",{"loader":"css-loader","options":{"sourceMap":false}}],"less":["vue-style-loader",{"loader":"css-loader","options":{"sourceMap":false}},{"loader":"less-loader","options":{"sourceMap":false}}],"sass":["vue-style-loader",{"loader":"css-loader","options":{"sourceMap":false}},{"loader":"sass-loader","options":{"indentedSyntax":true,"sourceMap":false}}],"scss":["vue-style-loader",{"loader":"css-loader","options":{"sourceMap":false}},{"loader":"sass-loader","options":{"sourceMap":false}}],"stylus":["vue-style-loader",{"loader":"css-loader","options":{"sourceMap":false}},{"loader":"stylus-loader","options":{"sourceMap":false}}],"styl":["vue-style-loader",{"loader":"css-loader","options":{"sourceMap":false}},{"loader":"stylus-loader","options":{"sourceMap":false}}]},"cssSourceMap":false,"cacheBusting":true,"transformToRequire":{"video":["src","poster"],"source":"src","img":"src","image":"xlink:href"}}!./src/views/iot-supervise/truck/truck-carousel.vue?vue&type=style&index=0&lang=css& 4:14-1577 14:3-18:5 15:22-1585
@ ./src/views/iot-supervise/truck/truck-carousel.vue?vue&type=style&index=0&lang=css&
@ ./src/views/iot-supervise/truck/truck-carousel.vue
@ ./src/views lazy ^./.*$
@ ./src/authority/generate-routes.js
@ ./src/store/modules/user.js
@ ./src/store/index.js
@ ./src/main.js
@ multi (webpack)-dev-server/client?http://localhost:9532 webpack/hot/dev-server babel-polyfill ./src/main.js
分析：这里面的错误是关于postcss-loader的，只要将config/index.js中dev.cssSourceMap设置为true即可。
警告1(svg-sprite-loader)
升级过程中还遇到了一个警告，虽然不影响功能，但是看着还是很难受的。
in ./src/icons/svg/workList.svg
svg-sprite-loader exception. 28 rules applies to D:coolluprojectscoollu-v3source-codev1.0.1update-elementui-testsrciconssvgworkList.svg
@ ./src/icons/svg .svg$
@ ./src/icons/index.js
@ ./src/main.js
@ multi (webpack)-dev-server/client?http://localhost:9532 webpack/hot/dev-server babel-polyfill ./src/main.js
搜索关键词后，发现网上并没有此类答案。因此我考虑是版本问题，于是升级svg-sprite-loader至最新版本4.1.6，解决了这个警告问题。
总结
至此升级过程就完成了！顺便一提，系统性升级必须要经过全面测试，否则你难以保证完全向下兼容哦！