npm install Error: rollbackFailedOptional

Question

When I try npm install new packages it shows me this error:

rollbackFailedOptional: verb npm-session 585aaecfe5f9a82

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Answer 1

Most likely to be npm registry cannot be reached by npm. Check npm proxy configuration

I had exactly the same issue on Windows Server 2008 R2. I suspected Internet Explorer's Enhanced Security Configuration at first but after turning that off with no success the issue turned out to be that npm was not configured to use my corporate proxy connection to the internet.

It turns out that npm does not use the proxy settings in effect via Internet Options > Connections tab > LAN settings where the server is set to 'Automatically detect settings'. Being set to automatically detect settings does not guarantee that a proxy is indeed being used, it just means that Windows will automatically configure proxy settings for Internet Explorer if it finds a special'wpad.dat' file at http://wpad.[yourdomain.com]/wpad.dat.

You can test whether a wpad.dat file is in use in your organisation by typing the following into a web browser.

http://wpad.[yourcompany.domain]/wpad.dat

If no file is available then it is likely you are not using an organization-wide proxy. If one does get returned to the browser then...

Toward the bottom of this file, you should see a line saying

PROXY ;

It might be repeated if you have multiple proxies available. The host and port are needed in order to tell npm to use the proxy settings like so:

npm config set proxy http://[host]:[port]

and

npm config set https-proxy http://[host]:[port]

For example if your proxy is at my.proxy.com on port 8080 then the npm commands would be:

npm config set proxy http://my.proxy.com:8080
npm config set https-proxy http://my.proxy.com:8080

Once I had told npm which proxy to use all started working in I was able to run the install commands without a problem.

Thanks to the following post for help with the wpad file discovery.