brew installation of Python 3.6.1: [SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed

I installed python 3.6 using

brew install python3

and tried to download a file with six.moves.urllib.request.urlretrieve from an https, but it throws the error

ssl.SSLError: [SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed (_ssl.c:749)

In the Python installation (from .pkg), the README indicates that one needs to run the Install Certificates.command after the installation to

1. install certifi
2. symlink the certification path to certify path

to be able to use certificates.

However, in brew install, this file does not exist and it does not seem to be run.

Answers:

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Method 1

It seems that, for some reason, Brew has not run the Install Certificates.command that comes in the Python3 bundle for Mac. The solution to this issue is to run the following script (copied from Install Certificates.command) after brew install python3:

# install_certifi.py
#
# sample script to install or update a set of default Root Certificates
# for the ssl module.  Uses the certificates provided by the certifi package:
#       https://pypi.python.org/pypi/certifi

import os
import os.path
import ssl
import stat
import subprocess
import sys

STAT_0o775 = ( stat.S_IRUSR | stat.S_IWUSR | stat.S_IXUSR
             | stat.S_IRGRP | stat.S_IWGRP | stat.S_IXGRP
             | stat.S_IROTH |                stat.S_IXOTH )


def main():
    openssl_dir, openssl_cafile = os.path.split(
        ssl.get_default_verify_paths().openssl_cafile)

    print(" -- pip install --upgrade certifi")
    subprocess.check_call([sys.executable,
        "-E", "-s", "-m", "pip", "install", "--upgrade", "certifi"])

    import certifi

    # change working directory to the default SSL directory
    os.chdir(openssl_dir)
    relpath_to_certifi_cafile = os.path.relpath(certifi.where())
    print(" -- removing any existing file or link")
    try:
        os.remove(openssl_cafile)
    except FileNotFoundError:
        pass
    print(" -- creating symlink to certifi certificate bundle")
    os.symlink(relpath_to_certifi_cafile, openssl_cafile)
    print(" -- setting permissions")
    os.chmod(openssl_cafile, STAT_0o775)
    print(" -- update complete")

if __name__ == '__main__':
    main()

Method 2

My solution for Mac OS X:

1) Upgrade to Python 3.6.5 using the native app Python installer downloaded from the official Python language website https://www.python.org/downloads/

I’ve found that this installer is taking care of updating the links and symlinks for the new Python a lot better than homebrew.

2) Install a new certificate using “./Install Certificates.command” which is in the refreshed Python 3.6 directory

cd “/Applications/Python 3.6/”
sudo “./Install Certificates.command”

Method 3

• find out default cafile:

python -c 'import ssl; print(ssl.get_default_verify_paths().openssl_cafile)'

/Applications/Xcode.app/Contents/Developer/Library/Frameworks/Python3.framework/Versions/3.7/etc/ssl/cert.pem

sudo mkdir -p /Applications/Xcode.app/Contents/Developer/Library/Frameworks/Python3.framework/Versions/3.7/etc/ssl/certs

• find out ca file of certifi

python -c 'import certifi; print(certifi.where())'

‘/usr/local/lib/python3.7/site-packages/certifi/cacert.pem’

• copy to

sudo cp /usr/local/lib/python3.7/site-packages/certifi/cacert.pem
/Applications/Xcode.app/Contents/Developer/Library/Frameworks/Python3.framework/Versions/3.7/etc/ssl/certs/cert.pem

Method 4

For temporary, following will disable the ssl checking,

import ssl
ssl._create_default_https_context = ssl._create_unverified_context

Method 5

If you need to make your local root certificate (e.g. local_RootCA.crt) become trusted by python, you can add it into the end of certifi/cacert.pem file:

cat local_RootCA.crt >> `python -c 'import certifi; print(certifi.where())'`

That solution works good for macos brew python 3 installation as well.

All methods was sourced from stackoverflow.com or stackexchange.com, is licensed under cc by-sa 2.5, cc by-sa 3.0 and cc by-sa 4.0