When I update to latest version, It didn't work by Error: Cannot find module 'reflect-metadata'

Ionic version: (check one with “x”) [ ] 1.x [x] 2.x

I’m submitting a … (check one with “x”) [x] bug report [ ] feature request [ ] support request => Please do not submit support requests here, use one of these channels: https://forum.ionicframework.com/ or http://ionicworldwide.herokuapp.com/

After I update ionic CLI to version 2.1.17 and create a new project by command: ionic start projectxxx --v2 tabs

Then I try: cd projectxxx ionic serve

Then it throw an exception:

C:\Users\Administrator\Documents\ionic\ionv2>ionic serve

> ionic-app-base@ ionic:serve C:\Users\Administrator\Documents\ionic\ionv2
> ionic-app-scripts serve
module.js:327
    throw err;
    ^

Error: Cannot find module 'reflect-metadata'
    at Function.Module._resolveFilename (module.js:325:15)
    at Function.Module._load (module.js:276:25)
    at Module.require (module.js:353:17)
    at require (internal/module.js:12:17)
    at Object.<anonymous> (C:\Users\Administrator\Documents\ionic\ionv2\node_modules\@ionic\app-scripts\dist\aot\aot-compiler.js:4:1)
    at Module._compile (module.js:409:26)
    at Object.Module._extensions..js (module.js:416:10)
    at Module.load (module.js:343:32)
    at Function.Module._load (module.js:300:12)
    at Module.require (module.js:353:17)
    at require (internal/module.js:12:17)

npm ERR! Windows_NT 10.0.14393
npm ERR! argv "C:\\Program Files\\nodejs\\node.exe" "C:\\Program Files\\nodejs\\node_modules\\npm\\bin\\npm-cli.js" "run" "ionic:serve" "--"
npm ERR! node v4.4.3
npm ERR! npm  v2.15.1
npm ERR! code ELIFECYCLE
npm ERR! ionic-app-base@ ionic:serve: \`ionic-app-scripts serve\`
npm ERR! Exit status 1
npm ERR!
npm ERR! Failed at the ionic-app-base@ ionic:serve script 'ionic-app-scripts serve'.
npm ERR! This is most likely a problem with the ionic-app-base package,
npm ERR! not with npm itself.
npm ERR! Tell the author that this fails on your system:
npm ERR!     ionic-app-scripts serve
npm ERR! You can get information on how to open an issue for this project with:
npm ERR!     npm bugs ionic-app-base
npm ERR! Or if that isn't available, you can get their info via:
npm ERR!
npm ERR!     npm owner ls ionic-app-base
npm ERR! There is likely additional logging output above.

npm ERR! Please include the following file with any support request:
npm ERR!     C:\Users\Administrator\Documents\ionic\ionv2\npm-debug.log
There was an error serving your Ionic application: There was an error with the spawned command: serve

Then I try start a project by ionic v1,It works!

So,how to fix it in ionic v2.