Node Js: Error - Unable to verify leaf signature when installing Express Framework

Question

I need to install Express Framework for my application.
This is the error which I am obtaining. I tried to set Environment varaibales for my computer towards npm as http://username:password@proxy:port for both http and https.

Also, I have tried the code such as

npm config set proxy http://username:password@proxy:port -g
npm config set https-proxy http://username:password@proxy:port -g
npm config set strict-ssl false.

Even then I am getting the below error.

 npm ERR! node v0.12.7
    npm ERR! npm  v2.11.3
    npm ERR! code UNABLE_TO_VERIFY_LEAF_SIGNATURE

    npm ERR! unable to verify the first certificate
    npm ERR!
    npm ERR! If you need help, you may report this error at:
    npm ERR!     <https://github.com/npm/npm/issues>

    npm ERR! Please include the following file with any support request:

Any help regarding installing Express Framework would be appreciated.

Answer 1

I have also faced same problem, but your last option i.e.

npm config set strict-ssl false worked for me.

after run this command in command prompt I installed express framework with following command:

npm install -g express-generator