I can download MacOS Big Sur, but it will not install

Apple's own website specifies 10.9 (Mavericks) or later can upgrade directly to Big Sur. An intermediate MacOS updgrade is NOT necessary.

https://www.apple.com/macos/how-to-upgrade/

It also says here that an upgrade to Big Sur from your current MacOS release level requires up to 44.5GB of available storage. You may be really close to that limit.

https://support.apple.com/kb/sp833?locale=en_US

Are you receiving any error messages when attempting to install it?

drnoble29 wrote:

I can download MacOS Big Sur, but it will not install

Big Sur—Press release states that you will need 35.5 GB of free storage when upgrading from High Sierra or newer, and 44.5 GB when upgrading from an older versions.

Big Sur macOS 11.1 https://support.apple.com/macos

drnoble29 wrote:

I have 48.78 GB free out of 120.37

MacBook Air Early 2014

OS X just shows 10.9.5

Does not say Mojave or Sierra, but think is Mojave

OS X 10.9.5 is Mavericks —That is the original OS X that shipped on your MacBook Air 7 years ago.

You are so far behind, you will have to stair step up to at least to El Captain 10.12.6 or High Sierra 10.13.6 before you can proceed further.

macOS 10.13.6 High Sierra - Technical Specifications:

https://support.apple.com/kb/SP765?locale=en_US

https://itunes.apple.com/us/app/macos-high-sierra/id1246284741?ls=1&mt=12

How to upgrade to macOS High Sierra

https://support.apple.com/en-us/HT208969

    MacBook (Late 2009 or newer

    MacBook Pro (Mid 2010 or newer)

    MacBook Air (Late 2010 or newer)

    Mac mini (Mid 2010 or newer)

    iMac (Late 2009 or newer)

    Mac Pro (Mid 2010 or newer)

It never pays to get too far behind in the software or hardware, it only makes it more difficult to take a giant leap.

This may sound silly, but not knowing what's on your MBA, when you click the install, do you click the icon labeled "Macintosh HD, make sure you select it, and click "install"?

If you did, you click the install option, and it remains on the installation? Does it allow you to click the install button again?

Considering the age of your MBA and that you have so little available disk space, it may just be taking a bit long to begin the actual installation process.

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