If you're using an older Mac it's likely you have seen warnings or errors about SSL or certificate issues when browsing the internet etc. This can be frustrating but there's a reason behind it, and it can be fixed.

Why do these errors happen?

All modern computers use security certificates to make sure your internet connection is safe and that the websites you visit are genuine.

Security certificates have an expiry date, and when they do expire you are often prevented from visiting the website/accessing a service.

Since older versions of Mac OS X no longer receive updates from Apple, their certificates become outdated and you need to perform a manual update.

Step-by-Step Guide

By updating the certificates, you're giving your Mac the ability to recognize and trust modern websites again.

1. Download the new certificates:
   • Use another device to download the latest root certificates from Let's Encrypt (a trusted certificate authority).
   • If you're downloading this on a modern Mac, you may see a warning telling you that this file is a potential security risk. This warning can be ignored.
   • Transfer these to your older Mac (via USB, email, etc.).
2. Install the Certificates:
   • Once the certificate file has been transferred to the older Mac, open the certificate file.
   • This should open the 'Keychain Access' utility. Add the certificates to the 'System' keychain, not the 'login' keychain.
   • You may need to enter your system password and set each certificate to 'Always Trust.'
3. Restart Your Mac: Once you've installed the certificate you should reboot the computer.
4. Test the Connection: Open your web browser and visit a few websites. If all went well, you shouldn't see any more SSL errors.

Further Reading