Hi, I get the same error and no clue
Logs file here :
verbose stack Error: 404 Not Found: @nuxeo/polymer-build@^2.0.0
3251 verbose stack at fetch.then.res (C:\Program Files\nodejs\node_modules\npm\node_modules\pacote\lib\fetchers\registry\fetch.js:42:19)
3251 verbose stack at tryCatcher (C:\Program Files\nodejs\node_modules\npm\node_modules\bluebird\js\release\util.js:16:23)
3251 verbose stack at Promise._settlePromiseFromHandler (C:\Program Files\nodejs\node_modules\npm\node_modules\bluebird\js\release\promise.js:512:31)
3251 verbose stack at Promise._settlePromise (C:\Program Files\nodejs\node_modules\npm\node_modules\bluebird\js\release\promise.js:569:18)
3251 verbose stack at Promise._settlePromise0 (C:\Program Files\nodejs\node_modules\npm\node_modules\bluebird\js\release\promise.js:614:10)
3251 verbose stack at Promise._settlePromises (C:\Program Files\nodejs\node_modules\npm\node_modules\bluebird\js\release\promise.js:693:18)
3251 verbose stack at Async._drainQueue (C:\Program Files\nodejs\node_modules\npm\node_modules\bluebird\js\release\async.js:133:16)
3251 verbose stack at Async._drainQueues (C:\Program Files\nodejs\node_modules\npm\node_modules\bluebird\js\release\async.js:143:10)
3251 verbose stack at Immediate.Async.drainQueues (C:\Program Files\nodejs\node_modules\npm\node_modules\bluebird\js\release\async.js:17:14)
3251 verbose stack at runCallback (timers.js:789:20)
3251 verbose stack at tryOnImmediate (timers.js:751:5)
3251 verbose stack at processImmediate [as _immediateCallback] (timers.js:722:5)
3252 verbose cwd C:\Users\nuxeo\addons\nuxeo-web-ui
3253 verbose Windows_NT 10.0.14393
3254 verbose argv "C:\Program Files\nodejs\node.exe" "C:\Program Files\nodejs\node_modules\npm\bin\npm-cli.js" "install"
3255 verbose node v8.9.4
3256 verbose npm v5.6.0
3257 error code E404
3258 error 404 Not Found: @nuxeo/polymer-build@^2.0.0
