IMAC LATE 2013 UNABLE TO UPDATE

The Late-2013 iMac can only upgrade to Catalina (strictly 64-bit applications) or Mojave (32/64-bit applications). Before you upgrade, run the free Go64 application to show you which applications are 32-bit, and would not be compatible on Catalina unless the product vendor provides a 64-bit version for download.

Completely remove any anti-virus or so-called "cleaner" applications from the current operating system. Perform a final Time Machine backup of the current operating system, and then set that drive aside, not using it to backup the upgraded operating system.

Using strictly the Safari browser, visit How to get old versions of macOS, and click the link to the Mac App Store for the version of macOS you choose to upgrade too. It will download to your /Applications folder and prompt you to continue or quit the installer.

What macOS version is your Late 2013 iMac currently running?

see > https://support.apple.com/en-us/HT201260

I'll tell you a secret. Download the free app MacTracker and look up your Mac model in it. It makes us all look like Tim Cook clones. 😉

Yes Catalina is it for a Late 2013 iMac.

You’re welcome.

A new iMac (24-inch) will ship with macOS Monterey, and that means you cannot run any 32-bit applications on it, or any Microsoft supported Windows versions either. If 32-bit applications are not an issue from my previous post, then get the 8-core cpu/gpu model with 16GB RAM. I would not purchase below a 512 GB drive.

Although Apple still sells the 27-inch Intel iMac, there are present/future features in Monterey that may not support that Intel architecture and Apple is migrating away from Intel-based products entirely in the next few years.

Don't forget to purchase a suitable sized, USB-C Time Machine drive that is (2.5 - 3x) larger than the internal iMac storage

Again you’re welcome.

To be honest, I only know a small fraction, but try to learn something new every day. Well almost everyday. 😉