Python-mode: Can't load python-mode: E887

[miaton]

It used to work without problem. Recently it starts to show the following errors.

Error detected while processing function pymode#init:
line 2:
E887: Sorry, this command is disabled, the Python's site module could not be lo
ded.
line 3:
E887: Sorry, this command is disabled, the Python's site module could not be lo
ded.
line 4:
E887: Sorry, this command is disabled, the Python's site module could not be lo
ded.
Error detected while processing C:\Users\XX.vim\bundle\python-mode\autoload
pymode\virtualenv.vim:
line 3:
E887: Sorry, this command is disabled, the Python's site module could not be lo
ded.
Error detected while processing function pymode#breakpoint#init:
line 27:
E887: Sorry, this command is disabled, the Python's site module could not be lo
ded.
Error detected while processing C:\Users\XX.vim\bundle\python-mode\ftplugin
python\pymode.vim:

[miaton]

add the following to .vimrc solved the problem
let g:pymode_python = 'python3'