s running at http://localhost:3000/
webpack output is served from /
Content not from webpack is served from e:\1804vuedemo\vueroutermedo/dist
Hash: 6cf951ad079ff750702e
Version: webpack 3.11.0
Time: 942ms
     Asset       Size  Chunks                    Chunk Names
    app.js     325 kB       0  [emitted]  [big]  main
app.js.map     385 kB       0  [emitted]         main
index.html  352 bytes          [emitted]
   [2] multi (webpack)-dev-server/client?http://localhost:3000 ./src/main.js 40 bytes {0} [built]
   [3] (webpack)-dev-server/client?http://localhost:3000 7.95 kB {0} [built]
   [4] (webpack)/node_modules/url/url.js 23.3 kB {0} [built]
   [7] (webpack)/node_modules/url/util.js 314 bytes {0} [built]
   [8] (webpack)/node_modules/querystring-es3/index.js 127 bytes {0} [built]
  [11] (webpack)-dev-server/node_modules/strip-ansi/index.js 161 bytes {0} [built]
  [12] (webpack)-dev-server/node_modules/ansi-regex/index.js 135 bytes {0} [built]
  [13] (webpack)-dev-server/node_modules/loglevel/lib/loglevel.js 7.86 kB {0} [built]
  [14] (webpack)-dev-server/client/socket.js 1.05 kB {0} [built]
  [15] (webpack)-dev-server/node_modules/sockjs-client/dist/sockjs.js 181 kB {0} [built]
  [16] (webpack)-dev-server/client/overlay.js 3.73 kB {0} [built]
  [18] (webpack)-dev-server/node_modules/html-entities/index.js 231 bytes {0} [built]
  [21] (webpack)/hot nonrecursive ^\.\/log$ 170 bytes {0} [built]
  [23] (webpack)/hot/emitter.js 77 bytes {0} [built]
  [25] ./src/main.js 791 bytes {0} [built] [failed] [1 error]
    + 11 hidden modules

ERROR in ./src/main.js
Module build failed: Error: Cannot find module '@babel/core'
    at Function.Module._resolveFilename (internal/modules/cjs/loader.js:581:15)
    at Function.Module._load (internal/modules/cjs/loader.js:507:25)
    at Module.require (internal/modules/cjs/loader.js:637:17)
    at require (internal/modules/cjs/helpers.js:20:18)
    at Object.<anonymous> (e:\1804vuedemo\vueroutermedo\node_modules\babel-loader\lib\index.js:5:15)
    at Module._compile (internal/modules/cjs/loader.js:689:30)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:700:10)
    at Module.load (internal/modules/cjs/loader.js:599:32)
    at tryModuleLoad (internal/modules/cjs/loader.js:538:12)
    at Function.Module._load (internal/modules/cjs/loader.js:530:3)
 @ multi (webpack)-dev-server/client?http://localhost:3000 ./src/main.js

vue程序跑起来，一直显示Module build failed: Error: Cannot find module ‘@babel/core’错误，网上收了很多方法，但是都太复杂，也许本身原因不一样，可以试试这个！

npm i babel-loader@7.1.5 -D

直接安装的是6.26.3的版本，安装指定版本。然后npm run start ，问题解决。
希望对你有用！