Unable to open file on my old MacBook Air 2013

Mac OS X 10.8.* is Mountain Lion. I would be surprised if it could even access the Apple Support article that describes how to get the Sierra installer, given Internet-wide changes in https security.

How to download and install macOS - Apple Support

What file are you trying to open? Is it the disk image (.DMG) file containing the Sierra installer? If so, did you transfer it in such a way as to preserve its integrity as a binary file?

The issue is that is not that Sierra is the final destination – but that to get to High Sierra, Mojave, Catalina, or Big Sur, the OP may first need to upgrade that Mac to El Capitan or Sierra. El Capitan and Sierra installers are in .DMG files, which can be transferred with the help of a modern Mac or PC. Installers for High Sierra and above are behind App Store links, so unless you're running something new enough to work well with the App Store, the App Store links in the Apple Support article may be "a bridge too far." El Capitan or Sierra are much more likely to work as a starting point than Mountain Lion is.

There is a special Recovery mode startup key combination:

How to reinstall macOS - Apple Support

"If you used Option-Command-R to start up from Internet Recovery, you might get the latest macOS that is compatible with your Mac."

If you really want Sierra and not any newer macOS that your Mac might very well support, you might try these workarounds:

https://mrmacintosh.com/fixed-an-error-occurred-while-preparing-the-installation-macos-sierra-recovery-error/

MacTracker indicates that the Mid 2013 MacBook Airs can run Big Sur (though nothing higher).

Catalina or Big Sur would be enough to let you run current versions of Firefox and LibreOffice. (They also would break 32-bit applications.). But to get to anything higher than Sierra, you first need to get to El Capitan or Sierra so that you have a chance of using the App Store links in that Support article.

Ortonx9 wrote:

hey so i used this to get into internet recovery mode. it gave me an option to install macos big sur so that was great. however when i went to choose to disk(macintosh hd), it was grayed out and said “the operation couldn’t be completed. (com.apple.BuildInfo.preflight.error error 12.)”

Did you erase the target disk or volume as APFS before trying? i.e. in Recovery Disk Utility > View > Show all Devices and erase the topmost device (not volumes under it if you want to erase the whole device) as APFS (GUID) case insensitive. But backup before doing so or install to another volume or disk.

The installer should convert MacOS Extended to APFS but that does not always succeed. You could also try to do that manually via Disk Utility.

p.s. Monterey installer might refuse to install to a 3rd party device but that does not seem to be the case here.

https://eshop.macsales.com/Service/Knowledgebase/Article/53/809/Aura-SSDs-macOS-12x-Monterey-Install-Requirement?srsltid=AfmBOoq9hmRUb97jp4oth9EirPkhWrGbDnexjduVn7hgly9A_xfvCnuB

Matti Haveri wrote:

Did you erase the target disk or volume as APFS before trying?

There is no way for the OP to do that. The OP's MacBook Air is currently running 10.8 (Mountain Lion). APFS showed up in 10.13 (High Sierra). I believe that the High Sierra installer automatically converted internal SSDs from HFS+ to APFS, but I never read anything about whether installers for subsequent versions of macOS did that.

Servant of Cats wrote:

Matti Haveri wrote:

Did you erase the target disk or volume as APFS before trying?

There is no way for the OP to do that. The OP's MacBook Air is currently running 10.8 (Mountain Lion). APFS showed up in 10.13 (High Sierra).

Oh yes I did not notice that detail. So the OP must first upgrade to High Sierra for APFS support. AFAIR there were some rules whether MacOS Extended was automatically converted to APFS in some workflows but it might be best to do and verify that manually.

Possibly you will need to boot from an external drive before you can upgrade that MacBook Air to any version of macOS that likes to use APFS. If you're booted from the Recovery partition on an internal, HFS+-formatted drive, and the installer wants to reformat the whole drive as APFS, how, exactly, does that work? Wouldn't it be a bit like poking a screwdriver into a car transmission while it was running?

If you have a spare external drive, you could try erasing it, and seeing if Recovery Mode will let you install Big Sur onto it. Since Mountain Lion knows nothing about APFS, you would use Mac OS Extended (Journaled, NON-case-sensitive), and hope that the Big Sur installer could do any conversion to APFS that might be needed.