Can't Update MacBook OS

You can try to check this link.

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

Hello, Maisyraye.

To address a couple points in your post...

Maisyraye wrote:

Hi everyone. Trying to update the OS on my MacBook Air (2017).

Current OS is macOS High Sierra 10.13.6. I can only access a "software update" button on the "About This Mac" screen and it leads me to a broken-looking App store with no available update in sight.

Earlier today I somehow stumbled across some OS update page and ran an update that took 30 minutes...and it changed absolutely nothing. (Worth noting, I have plenty of storage space for an update to be downloaded to my computer)

...

Any and all help is appreciated. I just got a notification that one of my necessary apps for work will cease functioning soon if I can't get my OS updated.

Thanks all!

The broken-looking App store is happening to everyone using 10.13.6 High Sierra or earlier. The look is broken, but the function is still there. It's a lapse on Apple's end as they wrap up support for that version of the macOS.

The OS update you stumbled on was likely the latest security update for High Sierra. Yes, it will have taken about 3o minutes to install. No, nothing will appear to have changed, but there will have been some changes made "under the hood" of the OS version on your Mac. These (usually) automatic updates will only update the currently running version of macOS on your computer. To upgrade to a newer macOS version – High Sierra to Big Sur – requires you to take the action to do so.

The notification you got regarding you app will cease functioning is about that 32-bit app that you are using in High Sierra. It will continue to work in High Sierra, but if/when you upgrade to Catalina, it will no longer work. Catalina ends all support for 32-bit app in macOS. To find out what other apps you have that will not work in Catalina or newer macOS, go to https://www.stclairsoft.com/Go64/index.html and download the free Go64 utility. I strongly suggest you do that before upgrading any further. Any 32-bit apps that you have MUST BE UPDATED to be compatible with Catalina, or Big Sur.

And, by the way... These Mac models are compatible with macOS 11 Big Sur :

MacBook (2015 or later)

MacBook Air (2013 or later)

MacBook Pro (Late 2013 or later)

Mac mini (2014 or later)

iMac (2014 or later)

iMac Pro (2017 or later)

Mac Pro (2013 or later)

Back up your data, check your applications for compatibility, and click on Mojave, Catalina, or Big Sur. They're full-version upgrades and won't appear in the Updates list.

(200516)