Hello folks,

I am trying to install openproject on my Ubuntu machine. I followed the manual installation guide from https://www.openproject.org/open-source/download/manual-installation-guide/
But in the last step I encountered the failure as below output:

$ npm install

openproject@0.1.0 postinstall /home/openproject/openproject-ce
cd frontend && npm install

npm WARN package.json openproject-frontend@0.1.0 No repository field.
npm WARN package.json openproject-frontend@0.1.0 No license field.
npm ERR! Linux 3.11.0-26-generic
npm ERR! argv “/usr/local/bin/node” “/usr/local/bin/npm” “install”
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:
npm ERR! /home/openproject/openproject-ce/frontend/npm-debug.log

npm ERR! Linux 3.11.0-26-generic
npm ERR! argv “/usr/local/bin/node” “/usr/local/bin/npm” “install”
npm ERR! node v0.12.7
npm ERR! npm v2.11.3
npm ERR! code ELIFECYCLE
npm ERR! openproject@0.1.0 postinstall: `cd frontend && npm install`
npm ERR! Exit status 1
npm ERR!
npm ERR! Failed at the openproject@0.1.0 postinstall script ‘cd frontend && npm install’.
npm ERR! This is most likely a problem with the openproject package,
npm ERR! not with npm itself.
npm ERR! Tell the author that this fails on your system:
npm ERR! cd frontend && npm install
npm ERR! You can get their info via:
npm ERR! npm owner ls openproject
npm ERR! There is likely additional logging output above.

npm ERR! Please include the following file with any support request:
npm ERR! /home/openproject/openproject-ce/npm-debug.log
$

Someone met the same problem can suggest any solution for this ?
Any advices would be highly appreciated

According to the guide I should install the packages on Ubuntu 14.04 64 bit but I just installed on Ubuntu 12.04 32 bit.
Should I upgrade to Ubuntu 14.04 64bit ?

I enclosed the npm-debug.log for more detailed information.
Thank you