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

Mine was due to McAfee firewall. It is set to Ask mode, so should have popped up a prompt to ask for internet connection, but it didn't! Going into McAfee and (temporarily!) disabling the firewall allowed me to install.