I have a number of older machines that I use on a regular basis, so I’m no stranger to the struggles of not being able to browse current websites on older machines with older browsers and the typical SSL/TLS support issues that you run into. I was surprised to see this error this week on my 2008 Mac Pro running Mac OS X 10.11 El Capitan and a latest version of Chrome:
Looking at the certificate for any site not loading it looks like the certificate has expired:
I’m not seeing this on my other later/current machines though, so clearly something on these older machines is no longer getting updates. Browsing around a few other sites and seeing the same issue on many sites so it was not just limited to a single site, so I realized something else was going on. Some Googling found this article:
Following the steps to download the updated certificate from LetsEncrypt and install it into Keychain did the job.