Why Does Python Throw a \'certificate verify failed\' Error When Accessing HTTPS Websites?

Understanding "certificate verify failed" Error in Python

When attempting to retrieve data from a HTTPS website using Python, it's possible to encounter the following error:

certificate verify failed: unable to get local issuer certificate

This error occurs because Python cannot verify the security certificate of the website. By default, Python relies on its own set of trusted root certificates to verify website certificates. However, if the website's certificate is not signed by one of these trusted root certificates, Python will fail the verification process.

Solution: Installing System Certificates

One solution to this error is to install the website's security certificate into the system's trusted root certificate store. On a Mac, this can be achieved by running the following command in Terminal:

/Applications/Python\ 3.7/Install\ Certificates.command

This command will install the system's default set of trusted root certificates into Python's trusted certificate store.

Understanding the Role of Certificates

SSL certificates are used to establish a secure connection between a web browser and a web server. They contain information about the website's identity and are used to encrypt data transmitted between the two parties.

• Root certificates are certificates that have been issued by trusted certificate authorities (CAs).
• Intermediate certificates are certificates that have been issued by a CA that is not a root CA.
• Website certificates are certificates that have been issued by a CA to a specific website.

Additional Resources for Learning

To improve your understanding of SSL certificates and security, consider the following resources:

• [Mozilla Developer Network: SSL/TLS Certificates](https://developer.mozilla.org/en-US/docs/Glossary/Certificate)
• [Cloudflare: Understanding SSL Certificates](https://www.cloudflare.com/en-us/learning/ssl/understanding-ssl-certificates/)
• [SecurityBoulevard: SSL Certificate Hierarchy: A Simple Explanation](https://securityboulevard.com/2017/11/ssl-certificate-hierarchy-simple-explanation/)

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