iMac 27" Late 2013 won't update to Catalina
I'm trying to update macOS on my iMac to Catalina and I keep getting the message "Update not found, The requested version of macOS is not available. Any idea as to why?
iMac 27", macOS 10.14
No idea because you haven't provided sufficient information. I'll assume you looked for an update on the App Store rather than an upgrade using Software Update. So give this a try: Get macOS Catalina.