When i try to update my computer from catalina 10.15 to big sur, it says that the update is not found. is there a way to force an update?

when you get a "update not found" message, it usually means that the Mac is not compatible with a given macOS. could you please share your Mac model and model year with us. then we can tell you if it is Big Sur capable, and we can go from there.

that totally depends on which model of 2013 Mac you have.

if yours is shown as compatible above, please confirm and we can proceed from there.

I just noticed that you are not the original poster of this thread. you would probably get more attention if you started a New Thread.

Is late 2013 version too old for an upgrade

Oh my bad I meant

iMac (21 inch, Late 2013)

Processor 2,7 GHz Intel Core i5

Memory 8 GB 1600 MHz DDR3

Storage: 1T

Thank you for the prompt response

so, no. a 2013 iMac cannot upgrade to Big Sur. sorry.