我需要补充另一个答案，因为就像Craig Glennie一样，由于网上有许多提到这个问题的帖子，我进行了一次徒劳的追逐。

我正在使用MacPorts，我最初认为的Python问题实际上是MacPorts问题:它在安装openssl时没有安装根证书。解决方案是移植安装curl-ca-bundle，如本文所述。

$ cd $HOME
$ wget --quiet https://curl.haxx.se/ca/cacert.pem
$ export SSL_CERT_FILE=$HOME/cacert.pem

来源:https://access.redhat.com/articles/2039753

另一个水蟒解决方案。我在macOS上的Python 2.7环境中获得了CERTIFICATE_VERIFY_FAILED。事实证明conda路径很糟糕:

基地(3.7)环境:

>>> import ssl
>>> ssl.get_default_verify_paths()
DefaultVerifyPaths(cafile='/usr/local/anaconda3/ssl/cert.pem', capath=None, openssl_cafile_env='SSL_CERT_FILE', openssl_cafile='/usr/local/anaconda3/ssl/cert.pem', openssl_capath_env='SSL_CERT_DIR', openssl_capath='/usr/local/anaconda3/ssl/certs')

2.7 environment(路径不存在!)

DefaultVerifyPaths(cafile='', capath=None, openssl_cafile_env='SSL_CERT_FILE', openssl_cafile='/usr/local/anaconda3/envs/py27/ssl/cert.pem', openssl_capath_env='SSL_CERT_DIR', openssl_capath='/usr/local/anaconda3/envs/py27/ssl/certs')

解决办法:

cd /usr/local/anaconda3/envs/py27/
mkdir ssl
cd ssl
ln -s ../../../ssl/cert.pem

Try

PIP install——trusted.host pypi.python.org packagename

这对我很管用。

有些情况下，你不能使用不安全的连接或传递ssl上下文到urllib请求。这里我的解决方案基于 https://stackoverflow.com/a/28052583/6709778

在这种情况下，如果您想使用自己的证书文件

import ssl

def new_ssl_context_decorator(*args, **kwargs):
    kwargs['cafile'] = '/etc/ssl/certs/ca-certificates.crt'
    return ssl.create_default_context(*args, **kwargs)

ssl._create_default_https_context = ssl._create_unverified_context

或者您可以使用certifi中的共享文件

def new_ssl_context_decorator(*args, **kwargs):
    import certifi
    kwargs['cafile'] = certifi.where()
    return ssl.create_default_context(*args, **kwargs)

The SSL: CERTIFICATE_VERIFY_FAILED error could also occur because an Intermediate Certificate is missing in the ca-certificates package on Linux. For example, in my case the intermediate certificate "DigiCert SHA2 Secure Server CA" was missing in the ca-certificates package even though the Firefox browser includes it. You can find out which certificate is missing by directly running the wget command on the URL causing this error. Then you can search for the corresponding link to the CRT file for this certificate from the official website (e.g. https://www.digicert.com/digicert-root-certificates.htm in my case) of the Certificate Authority. Now, to include the certificate that is missing in your case, you may run the below commands using your CRT file download link instead:

wget https://cacerts.digicert.com/DigiCertSHA2SecureServerCA.crt

mv DigiCertSHA2SecureServerCA.crt DigiCertSHA2SecureServerCA.der

openssl x509 -inform DER -outform PEM -in DigiCertSHA2SecureServerCA.der -out DigicertSHA2SecureServerCA.pem.crt

sudo mkdir /usr/share/ca-certificates/extra

sudo cp DigicertSHA2SecureServerCA.pem.crt /usr/share/ca-certificates/extra/

sudo dpkg-reconfigure ca-certificates

在此之后，您可以再次使用wget测试URL，也可以使用python urllib包进行测试。详情请参考:https://bugs.launchpad.net/ubuntu/+source/ca-certificates/+bug/1795242