申请Let’s证书报错

申请Let’s证书报错：/opt/eff.org/certbot/venv/lib/python2.6/site-packages/cryptography/__init__.py:26: DeprecationWarning: Python 2.6 is no longer supported by the Python core team, please upgrade your Python. A future version of cryptography will drop support for Python 2.6
DeprecationWarning
Saving debug log to /var/log/letsencrypt/letsencrypt.log
Plugins selected: Authenticator webroot, Installer None
Missing command line flag or config entry for this setting:
You have an existing certificate that contains a portion of the domains you requested (ref: /etc/letsencrypt/renewal/quanzi.nmg520.cc.conf)