how to update to os x

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. Make sure to use Only Safari to commence the download as Other may not work

Make a Time Machine Backup Before attempting. Notation - Mojave is the Last version to support 32 bit applications / extensions and Drivers. Catalina and Big Sur Only support 64 bit and there is no workaround.

Are there any AntiVirus, Disk Cleaner, Optimizers, Defrag, VPNs etc installed which should be removed as per Developers Instructions. They are useless, unneeded, cause havoc and interfere with the normal operation of the OS and may even Corrupt the OS requiring a Reinstallation.

Disconnect any and all external drives and shutdown computer by any means including the Power Button. Connect to charger and restart and Immediately hold the SHIFT key until the Apple Logo appears and starts loading - then release Shift key. This is Safe Mode, does a repair disk, clears cache files and only loads Apple Software, extensions and fonts - - so loads slowly. This process may or may not allow the upgrade process to complete and the Drive conversion from HFS Journaled to the new APFS filing system offered on Apple SSDs on High Sierra

Back up your data, check your applications for compatibility, and if your MacBook Air is a late 2010 or newer model, click on High Sierra. Otherwise, you can't.

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