update will not download onto my Mac Big Sur 11.17.3

Update would mean an update of Big Sur to something like an Unknown version of Big Sur like version 11.7.4

An upGrade would be moving from macOS 11 Big Sur to macOS 12 Monterey or macOS 13 Ventura.

If the later is what is really meant >>

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.

With the above information in-hand - follow this How to get old versions of macOS and verify what version this computer Qualifies to install.  For Best results use Safari to commence the download as Others may not work.

Safari will open a redirect and open the Apple Store where the download can commence.

Does the computer appear and is listed as Qualifying for an upGrade ?

Computer Qualifying for macOS 13 Ventura 

Computer Qualify for the Monterey upgrade

Kenneth Martz wrote:

I believe there is a new security update for Big Sur taking it from 11.7.3 to 11.7.4. My Software Update App is stuck "cheking for updates". Don't know what my problem is.

There may be a Big Sur update or not; I don't know, but I understand Software Update is stuck at "Checking for updates..." with no end in sight.

Several workarounds have been proposed, such as restarting your Mac in "Safe Mode" and checking for updates while in that mode, and / or resetting NVRAM.

How to use safe mode on your Mac - Apple Support

Reset NVRAM on your Mac - Apple Support

Related: Software Update stuck at "Checking for updates"… - Apple Community

Replied to the wrong post above:

I believe there is a new security update for Big Sur taking it from 11.7.3 to 11.7.4. This sounds like what the original poster was describing.

I'm having trouble too. My Software Update App is stuck "checking for updates". Don't know what my problem is.

There are factors:

1 - Like poor Wifi connection

2 - Slow wifi connection

3 - Too many other people downloading at the same time and Apple Severs are overloaded

4 - Software on the computer interfering with the download process including AntiVirus Software

Notation: Disabling the AV Software may or may not solve the issue. Removal of the AV Software may increase the chances of the download to perform as expected.

5 - Running behind a VPN which may increase Packet losses or corruption of the download 

6 - If via wifi too many Other devices using the wifi at the same time reducing the Bandwidth to your computer. 

7 - Best Results are via Ethernet Cable to Router

softwareupdate --list-full-installers

Finding available software

Software Update found the following full installers:

* Title: macOS Big Sur, Version: 11.7.4, Size: 12119555KiB, Build: 20G1120, Deferred: NO

* Title: macOS Big Sur, Version: 11.7.3, Size: 12119247KiB, Build: 20G1116, Deferred: NO

* Title: macOS Big Sur, Version: 11.7.2, Size: 12119307KiB, Build: 20G1020, Deferred: NO

* Title: macOS Big Sur, Version: 11.7.1, Size: 12119247KiB, Build: 20G918, Deferred: NO

* Title: macOS Big Sur, Version: 11.6.6, Size: 12121263KiB, Build: 20G624, Deferred: NO

* Title: macOS Big Sur, Version: 11.6.5, Size: 12121404KiB, Build: 20G527, Deferred: NO

* Title: macOS Big Sur, Version: 11.6.4, Size: 12147782KiB, Build: 20G417, Deferred: NO

* Title: macOS Big Sur, Version: 11.6.3, Size: 12143674KiB, Build: 20G415, Deferred: NO

* Title: macOS Big Sur, Version: 11.6.2, Size: 12141944KiB, Build: 20G314, Deferred: NO

* Title: macOS Big Sur, Version: 11.6.1, Size: 12137180KiB, Build: 20G224, Deferred: NO

* Title: macOS Big Sur, Version: 11.5.2, Size: 12149332KiB, Build: 20G95, Deferred: NO

Please describe the update you want to download.

Writing an effective Apple Support Communities Question - Apple Community

Heads up.

Apple Did Release a Big Sur update to 11.7.4 on Wednesday Feb 15, 2023

Link below

Apple security updates - Apple Support (CA)

I believe there is a new security update for Big Sur taking it from 11.7.3 to 11.7.4. My Software Update App is stuck "cheking for updates". Don't know what my problem is.