OS X 10.11 El Capitan Certificates

I know OS X El Capitan is old, and I know it is not supported anymore, but I do have a question to try to squeeze some more life from it.

I help to manage several small Mac labs at a public high school, and we have to use older equipment until we get upgrades. Some of the Mac computers are stuck on OS X El Capitan as that is the newest version of the Mac Operating System that is supported.

I saw this thread and noticed this response by "webprofusion" to do the following on OS X El Capitan:

" For older macOS, try:

  • downloading https://letsencrypt.org/certs/isrgrootx1.der
  • Open the Keychain Access app and dragging that file into the System folder of that app.
  • then find the ISRG Root X1 certificate in System and double click on it, open the Trust menu and change "Use System Defaults" to "Always Trust", then close that and enter your password to confirm the change (if prompted)."

Is this solution trusted and secure for the time being on a total of 6 Mac computers stuck on OS X El Capitan?

I just wanted to ask and get more clarification from the community before adding a new certificate to 6 Macs.

Thank you.



Hi @Jack-19 and welcome to the LE community forum :slight_smile:

Yes, that is essentially a manual version of what Apple would have done if that OS was still being supported and it will definitely help you:


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