El Capitan to Catalina upgrade on iMac. 27 inch late 2012 model
Hello. I have a late 2012, 27 inch iMac currently running El Capitan. Apple lists this model as being compatible for an upgrade to OSX Catalina. However after doing a full backup of the iMac and then going to the Software Update section of About This Mac, there are no updates listed at all. Any help would be most appreciated.
Thanks.
iMac 27″, OS X 10.11