Install erpnext problem on ubuntu 16

hi i have install erpnext on fresh ubuntu 16 server but i have a problem. this is a step:

sudo apt-get update
sudo apt-get upgrade -y
sudo apt-get install python-minimal -y
wget https://raw.githubusercontent.com/frappe/bench/master/playbooks/install.py
sudo python install.py --production --user frappe --verbose

and this is a problem occured during installation:

T> ASK [Create new site] *********************************************************

task path: /tmp/.bench/playbooks/production/includes/setup_bench_production.yml: 13
ESTABLISH LOCAL CONNECTION FOR USER: root
127.0.0.1 EXEC /bin/sh -c ‘( umask 22 && mkdir -p “echo /tmp/ansible-tmp-14846 47655.93-6576933860005” && echo “echo /tmp/ansible-tmp-1484647655.93-6576933 860005” )’
127.0.0.1 PUT /tmp/tmpGByO8G TO /tmp/ansible-tmp-1484647655.93-6576933860005/com mand
127.0.0.1 EXEC /bin/sh -c ‘chmod a+r /tmp/ansible-tmp-1484647655.93-657693386000 5/command’
127.0.0.1 EXEC /bin/sh -c ‘sudo -H -S -n -u frappe /bin/sh -c ‘"’"‘echo BECOME-S UCCESS-kmiymxmnbpbkwczjukgkjblldsxzkqdi; LANG=it_IT.UTF-8 LC_ALL=it_IT.UTF-8 LC_ MESSAGES=it_IT.UTF-8 /usr/bin/python /tmp/ansible-tmp-1484647655.93-657693386000 5/command’"’"’’
127.0.0.1 EXEC /bin/sh -c ‘rm -f -r /tmp/ansible-tmp-1484647655.93-6576933860005 / > /dev/null 2>&1’
An exception occurred during task execution. The full traceback is:
Traceback (most recent call last):
File “/tmp/ansible-tmp-1484647655.93-6576933860005/command”, line 2433, in
main()
File “/tmp/ansible-tmp-1484647655.93-6576933860005/command”, line 222, in main
args = shlex.split(args)
File “/usr/lib/python2.7/shlex.py”, line 279, in split
return list(lex)
File “/usr/lib/python2.7/shlex.py”, line 269, in next
token = self.get_token()
File “/usr/lib/python2.7/shlex.py”, line 96, in get_token
raw = self.read_token()
File “/usr/lib/python2.7/shlex.py”, line 172, in read_token
raise ValueError, “No closing quotation”
ValueError: No closing quotation

fatal: [localhost]: FAILED! => {“changed”: false, “failed”: true, “invocation”: {“module_name”: “command”}, “module_stderr”: “Traceback (most recent call last): \n File “/tmp/ansible-tmp-1484647655.93-6576933860005/command”, line 2433, in \n main()\n File “/tmp/ansible-tmp-1484647655.93-6576933860005/com mand”, line 222, in main\n args = shlex.split(args)\n File “/usr/lib/pytho n2.7/shlex.py”, line 279, in split\n return list(lex)\n File “/usr/lib/pyt hon2.7/shlex.py”, line 269, in next\n token = self.get_token()\n File “/us r/lib/python2.7/shlex.py”, line 96, in get_token\n raw = self.read_token()\n File “/usr/lib/python2.7/shlex.py”, line 172, in read_token\n raise Value Error, “No closing quotation”\nValueError: No closing quotation\n”, “module_st dout”: “”, “msg”: “MODULE FAILURE”, “parsed”: false}

NO MORE HOSTS LEFT *************************************************************
to retry, use: --limit @production/install.retry

PLAY RECAP *********************************************************************
localhost : ok=49 changed=28 unreachable=0 failed=1

Traceback (most recent call last):
File “install.py”, line 351, in
install_bench(args)
File “install.py”, line 111, in install_bench
run_playbook(‘production/install.yml’, sudo=True, extra_vars=extra_vars)
File “install.py”, line 301, in run_playbook
success = subprocess.check_call(args, cwd=os.path.join(cwd, ‘playbooks’))
File “/usr/lib/python2.7/subprocess.py”, line 541, in check_call
raise CalledProcessError(retcode, cmd)
subprocess.CalledProcessError: Command ‘[‘ansible-playbook’, ‘-c’, ‘local’, ‘pro duction/install.yml’, ‘-e’, ‘@/tmp/extra_vars.json’, ‘-vvvv’, ‘–become’, ‘–bec ome-user=frappe’]’ returned non-zero exit status 2

What is memory of your server? I think you need at least 2 GB

the server has 2 gb of ram. any help for solve this error?