This has been fixed in versions of npm newer than so update to npm login errors You might try moving your npm-shrinkwrap.json file out of the way until we have this fixed. We're working on fixing this one, but it's a fairly subtle race condition and it's taking us a little time. cb() never called! when using shrinkwrapped dependencies If the problem persists, look at npm/npm#6043 and see if somebody has already discussed your issue. If you see ENOENT lstat, ENOENT chmod, ENOTEMPTY unlink, or something similar in your log output, try updating npm to the latest version.
As of npm 2.0.0, a very large number of these issues were addressed. Sometimes this results in race conditions and other synchronization issues. Npm is written to use resources efficiently on install, and part of this is that it tries to do as many things concurrently as is practical.
Windows: If you're on Windows and you have a broken installation, the easiest thing to do is to reinstall node from the official installer (see this note about installing the latest stable version).npm not running the latest version on a Windows machine.npm hangs on Windows at addRemoteTarball.cb() never called! when using shrinkwrapped dependencies.Many ENOENT / ENOTEMPTY errors in output.npm only uses git: and ssh+git: URLs for GitHub repos, breaking proxies.Running a Vagrant box on Windows fails due to path length issues.Error: ENOENT, stat 'C:\Users\\AppData\Roaming\npm' on Windows 7.