Certificate error on julialang.org

Was promoting Julia to some friends, they found julialang.org and clicked on some link at the top which gave them a white screen with an error saying something about a certificate missmatch, this prompted them to immediately leave the site… Have tried every link they could have clicked and all work here, what could have caused this?

There was an issue with the website a couple of days ago for a few hours, at which time users saw a “certificate mismatch” error. Are they still seeing that? in that case, some screenshots would be good.

Found a thread here on the same issue created at the time of occurrence so no worries