When I update my macOS, I get ERROR_5BCD167D29

Mac OS 13.X is Ventura, the last version of Ventura was 13.3. The earliest iMac that would run Catalina was a 2012 iMac, again you haven't stated the model year of the iMac you own.

If you need to run later versions of Mac OS and your iMac is 2012 or thereabouts then yes, you need to get a much more up-to-date Mac in order to run current versions of Mac OS. For Catalina's tech specs please click macOS Catalina - Technical Specifications - Apple Support

Crackles wrote:

Sorry! Yes there is an update for the Mac OS, I’m on 13.1, and the update is the latest. Previously it has said that I can’t update it because the Mac is too old, but the software version requirements says 13.1 or greater, so not sure why it won’t update, however I suspect the actual version is higher than 13.1, but only displays one decimal point of the file version. I’m picking it is in the later version (13.1.xxxx) is what is required

macOS 13.1 ( 22C65 ) was released Dec 13, 2022

There was a macOS 13.2.1 ( 22D68 ) released Feb 13, 2023

The very lasted version of macOS Ventura is now version 13.6.6

About the security content of macOS Ventura 13.6.6

Suggest follow the info from below link regarding the error message

If an error occurred while updating or installing macOS - Apple Support

Follow on

The Age of this computer will Govern what newer version of macOS it will Qualify to install. 

Use About this Mac from the Apple Icon on Desktop - the required Information will be there.

Does this computer appear as Listed and qualifying for an upGrade to a newer version of macOS ? 

macOS Sonoma is compatible with these computers

Computer Qualifying for macOS 13 Ventura 

Mac computers do not run IOS they use Mac OS? Do you mean Mac OS? If so you need to provide context so we know what you are experiencing. Please also let us know what version of Mac OS is currently installed and version you are trying to install!!!!