Which iMac do you have?

I have a 2005 one and a 2003 MBA, both updated to latest MacOS and only today I needed to exchange something between them on iCloud Drive so they clearly both have no issue with it.

I have an old 2009 iMac which runs High Sierra (probably the last MacOS it will support), which I haven't updated. I will do that and let you know if it is also OK.

Posted By: Steve in Holland, Apr 10, 14:30:42