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

看一看

/Applications/Python 3.6/Install Certificates.command

您也可以进入Finder中的Applications文件夹，然后单击Certificates.command

I was getting the same error, and also went on a wild goose chase for quite a while before I gave up and started trying things on my own. I eventually figured it out, so I thought I'd share. In my case, I am running Python 2.7.10 (due to reasons beyond my control) on Linux, don't have access to the requests module, can't install certificates globally at the OS or Python level, can't set any environment variables, and need to access a specific internal site that uses internally issued certificates.

注意:禁用SSL验证从来不是一个选项。我正在下载一个脚本，它可以立即以根用户的身份运行。没有SSL验证，任何web服务器都可以假装是我的目标主机，而我只是接受他们给我的任何东西，并以root身份运行它!

我将根证书和中间证书(可能不止一个)以pem格式保存到一个文件中，然后使用以下代码:

import ssl,urllib2
data = urllib2.build_opener(urllib2.HTTPSHandler(context=ssl.create_default_context(cafile='/path/to/ca-cert-chain.pem')), urllib2.ProxyHandler({})).open('https://your-site.com/somefile').read()
print(data)

注意，我在那里添加了urllib2.ProxyHandler({})。这是因为在我们的环境中，代理是默认设置的，但它们只能访问外部站点，不能访问内部站点。如果没有代理绕过，我就无法访问内部站点。如果你没有这个问题，你可以简化如下:

data = urllib2.build_opener(urllib2.HTTPSHandler(context=ssl.create_default_context(cafile='/path/to/ca-cert-chain.pem'))).open('https://your-site.com/somefile').read()

工作起来很有魅力，而且不会危及安全。

享受吧!

在我的情况下，我得到这个错误，因为请求和urllib3版本不兼容，在安装期间给出以下错误:

ERROR: requests 2.21.0 has requirement urllib3<1.25,>=1.21.1, but you'll have urllib3 1.25 which is incompatible.

pip install 'urllib3<1.25' --force-reinstall

成功了。

我通过关闭Fiddler(一个HTTP调试代理)来解决这个问题，检查是否启用了代理并重试。

你可以试着把这个添加到你的环境变量中:

PYTHONHTTPSVERIFY=0 

请注意，这将禁用所有HTTPS验证，所以这是一个大锤式的方法，但如果不需要验证，这可能是一个有效的解决方案。