Which is the newest OS I can upgrade a 24" early 2009 iMac?
Nowadays the user cannot access some https sites because "The connection is not private" or something similar depending on the browser used: ERR_CERT_DATE_INVALID despite it is valid. I can browse those sites from my Big Sur
I found that those sites have in common their certificates were issued by R3 Let's Encrypt.
letsencrypt.org/docs/certificate-compability states that macOS<10.12.1 will no longer validate their certificates as from Oct 1, 2021
So 10.12 is needed at least.
Will this iMac work okay with this OS? The user mostly uses web services, no need to run hard software.
How to upgrade?
Thank you
[Image Edited by Moderator to Remove Serial Number]