I read the wiki "https://github.com/Valloric/YouCompleteMe/wiki/Building-Vim-from-source".@H_301_1@ But it misleads me.

Please DO NOT configure vim like this on Ubuntu 14.04.5 LTS

--enable-pythoninterp=yes@H_301_1@ --with-python-config-dir=/usr/lib/python2.7/config@H_301_1@ --enable-python3interp=yes@H_301_1@ --with-python3-config-dir=/usr/lib/python3.5/config

Make sure only select one from python2 or python3.