mac下 python 报错 CERTIFICATE_VERIFY_FAILED
python 下载时， 报错如下：
ERROR: Unable to download webpage: <urlopen error [SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed (_ssl.c:581)> (caused by URLError(SSLError(1, u'[SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed (_ssl.c:581)'),))
多方搜索，得到错误原因urllib and “SSL: CERTIFICATE_VERIFY_FAILED” Error
根据 Craig Glennie分析如下：
This isn't a solution to your specific problem, but I'm putting it here because this thread is the top Google result for "SSL: CERTIFICATE_VERIFY_FAILED", and it lead me on a wild goose chase.
If you have installed Python 3.6 on OSX and are getting the "SSL: CERTIFICATE_VERIFY_FAILED" error when trying to connect to an https:// site, it's probably because Python 3.6 on OSX has no certificates at all, and can't validate any SSL connections. This is a change for 3.6 on OSX, and requires a post-install step, which installs the certifi package of certificates. This is documented in the ReadMe, which you should find at /Applications/Python\ 3.6/ReadMe.rtf
The ReadMe will have you run this post-install script, which just installs certifi: /Applications/Python\ 3.6/Install\ Certificates.command
Release notes have some more info: https://www.python.org/downloads/release/python-360/
解决方法：
步骤 1： 重新安装 certifi: pip3 install certifi
步骤 2： 执行 /Applications/Python\ 3.6/Install\ Certificates.command