what OS is before Big Sur. i have a 2010 iMac and need to upGrade

crecencia1 Said:

"what OS is before Big Sur. i have a 2010 iMac and need to upGrade"

-------

Incompatibility is the Culprit:

Installing Big Sur (macOS 11) is of no option. Your device only goes the High Sierra (macOS 10.13). Visit the link provided atop this post.

Your 2010 iMac cannot upgrade to any of the newer OS's, it does not meet the hardware requirements.

The last OS for a 2010 iMac is macOS High Sierra, are you interested in upgrading to that.

Open Safari and click on this link, 

How to get old versions of macOS – Apple Support

Go to the Download OS section and click on macOS High Sierra.

Before upgrading make a full back up of your Mac.

Check that third party apps you use have updates available for the new OS.

https://roaringapps.com

Check that your printers/ scanners etc have updated drivers and software available for the new OS.

Connect your mac to your router via cable rather than rely on WiFi.

Do not use your mac while it is downloading

and do not use any other devices that share the same internet connection.

If the App Store says ‘Open’ then it is detecting a previous download of the install app

go to the Applications folder locate Install macOS High Sierra.app.

Move it to the Trash, empty the Trash.

Restart, click on the link again, the App Store should say ‘Get' or 'Download'.

If it is still of interest to you macOS Catalina 10.15 was the OS before macOS Big Sur11.

You are welcome.