macOS High Sierra 10.13.6
how to upgrade the system from macOS 10.13.6 to the latest version?
MacBook Air 13″, macOS 10.13
Back up your data, check the application compatibility table, click here, and if your MacBook Air is a 2012 or newer model, then on the download link for a more-recent OS.
Catalina and higher won't run 32-bit software; if you upgrade to one of them, use Go64 as well.
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