How can I update my unsupported 2019 iMac to macOS 26?

Question

Level 1

4 points

How can I update my unsupported 2019 iMac to macOS 26?

I had a 2013 iMac and Time Machine. I replaced this with a 2019 iMac but linked the screens with thunderbolt cable . I also replaced the Time Machine, now not supported, with iCloud so do not have a local backup.

my 2019 iMac will not update to Mac os26.

is there some hardware that can sit in front of my IMac to give a firewall /virus protection and enable safe use on the internet?

is there a way to use the hard drive of the old iMac as local backup?

both products seem ok to use and a shame to scrap?

sorry if I have asked three questions but to me it is all related.

[Re-Titled by Moderator]

Original Title: Un- supported iMac 2019

iMac 21.5″, macOS 15.7

Posted on Dec 18, 2025 2:10 AM

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Answer 1

Owl-53

Level 10

102,547 points

Dec 18, 2025 3:03 AM in response to jed9parkcr

To specifically answer this stated question " How can I update my unsupported 2019 iMac to macOS 26?

Answer - NO, Full Stop .

No respectable and responsible contributor would assist in installing Tahoe on a Un-Qualified computer

Computers that Qualify to run macOS 26 Tahoe

macOS Tahoe is compatible with these computers

iMac (24-inch, 2024, Four ports)
iMac (24-inch, 2024, Two ports)
iMac (24-inch, 2023, Four ports)
iMac (24-inch, 2023, Two ports)
iMac (24-inch, M1, 2021)
iMac (Retina 5K, 27-inch, 2020)

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Answer 2

dialabrain

Level 10

135,875 points

Dec 18, 2025 3:04 AM in response to jed9parkcr

A few things…

It's perfectly safe to run a Mac with Sequoia as long as you keeep it up to date, now 15.7.3. And you follow some simple precautions…

Effective defenses against malware and ot… - Apple Community

Recognize and avoid social engineering schemes including phishing messages, phony support calls, and other scams - Apple Support

iCloud is not a substitute for Time Machine. Not sure what you mean by it's "not supported".

Personally I wouldn't even try to use a 12 year old hard drive. It won't last that much longer.

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Answer 3

Owl-53

Level 10

102,547 points

Dec 18, 2025 3:12 AM in response to jed9parkcr

The best this iMac from 2019 might run would be macOS 15 Sequoia which would continue to receive Bug and Security updates for a few more years

Though, no added features

macOS Sequoia is compatible with these computers

iMac (24-inch, 2024, Four ports)
iMac (24-inch, 2024, Two ports)
iMac (24-inch, 2023, Four ports)
iMac (24-inch, 2023, Two ports)
iMac (24-inch, M1, 2021)
iMac (Retina 5K, 27-inch, 2020)
iMac (Retina 5K, 27-inch, 2019)
iMac (Retina 4K, 21.5-inch, 2019)

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