macOS can’t install

BlueGamingKing wrote:

I first had macOS Sierra on my macbook (when he was still doing it) so I'd like to have it again.

You seem to believe—incorrectly—that old software will continue to work in an interconnected world. Connectivity can and does age out. App updates age out. Security exploits are identified. Sooner or later, you have apps or web sites that don’t work. Sometimes for obscure-looking or cryptic reasons.

For complete wipe, erase, and re-install of the current Catalina, clobbering all data and all files, including all user data...

Boot Recovery with option-command-R. Follow the link for details.

Use Disk Utility to erase Apple SSD SM0128G Media. Select format APFS, and select scheme GUID partition map.Follow the link for details.

Exit Disk Utility back to the main Recovery screen, and then install macOS Catalina on Apple SSD SM0128G Media.

Reboot into the new install. This’ll be the default bootstrap.

You’ll be prompted for and have a wholly new install, new passwords, new software, and the entire previous contents and all previous files and documents will be expunged; complete erasure of all precious system data, all apps, and all of your own user data.

1. Boot into Recovery mode (press and hold Option-Command-R or Shift-Option-Command-R at startup).
2. From the main menu, go into Disk Utilities to erase the entire internal drive (APFS)
3. Go back to the main menu then go to Install macOS (it might say reinstall macOS).
4. Follow the instructions

Good luck!

If this is a recently-purchased Mac, it cannot boot Sierra.

Assuming this Mac can boot Sierra—which is not yet certain, as you’ve not identified exactly which Mac and which model year is involved here—you will want to erase (“wis”) the highlighted (AppleAPFSMedia) device, and reformat that physical device (“Apple SSD SM01...”) using GUID/GPT partitioning and HFS+.

All contents of the erased device will be lost; erased; deleted; gone.

Then install Sierra, and allow the installer to partition the device as is the default. The “Preboot” and other entries in the above are partitions on the device. These are parts of the macOS installation, when APFS is in use on a macOS boot disk.

Sierra is off support, not getting security patches, and some Sierra installer downloads have been problematic, and a Mac running Sierra will be having increasing difficulties making secure connections as the software ages out. Basically, this path gets messy, and eill only get messier. Basically, this gets messy, and you’re probably not looking for this mess unless you really need Sierra. And High Sierra can install on most any Mac that can run Sierra, and is getting security patches, and can be easier to get working downloads. Etc. Downgrades aren’t all that fun, and the further back the less fun...

I very much would discourage this downgrade, if it’s even possible to install Sierra here.

With that selection under the cursor still highlighted in blue as shown, move the cursor to and click on the circled “wis” button.That’s erase. That erases. Everything.

That’ll offer up some options. Select APFS format with GUID partitioning scheme.

Wis is Erase in Dutch, yes?

Right now, you will end up installing macOS Sierra once you reformat the drive. You have to reformat the drive as I said in order to do that. Sierra can't install to an APFS formatted drive.

BlueGamingKing wrote:

But, can you explain it to me in steps. I don’t understand what i do now.

Please identify which Mac and which year, so that I can tailor the instructions. If you’re not sure, there’s usually a model code in tiny print on the bottom of the Mac. That’ll narrow this to one or maybe a few models of Mac.

Then please elaborate on your needs specifically around Sierra, and which apps are involved, as that downgrade can cause increased effort both for getting there—assuming Sierra is compatible with this Mac—and increasing effort maintaining this Mac. And there may be alternative approaches available to better meet those same needs.

With that info, I can provide a step-by-step.

Okay, MacBook Air 2017 will usually work as far back as macOS Sierra 10.12.4. The tiny-print model code on the bottom should be A1466.

Now, two more questions.

Are there particular apps that you need here, that absolutely need Sierra?

And what backups are available from prior to the re-installation efforts?

BlueGamingKing wrote:

what do you mean by apps that need Sierra, I have never made a backup copy of my macbook

Sierra (macOS 10.12) is outdated. The usual reason to re-install Sierra is to run old apps. Newer apps and current apps are compatible with and can run on High Sierra (macOS 10.13), Mojave (macOS 10.14), and Catalina (macOS 10.15); on the more recent and current macOS versions.

Okay, next, is there anything stored on this MacBook Air that you want to keep? Because the path that we’re currently on here produces a MacBook Air with just the Apple software installed, and no user accounts, no add-on apps, no documents, and no user files remaining.

If you want to keep the apps or data or files installed here, we may still be able to salvage those files, depending on exactly what’s happened so far.

Okay; so wholesale erasure and re-installationcan happen.

Now, before I write up the sequence and post it here, are your apps compatible with Catalina?

Microsoft Office 2016, Microsoft Office 2019, and Microsoft Office 365 are. Older Office versions are not. There are some other older apps that are not compatible with Catalina, too.

BlueGamingKing wrote:

so I have to delete the apple ssd sm0128gb disk? I don't want to do anything wrong so I just ask you to be sure.

You once stated your goal: ”I wanted to clear my macbook so I deleted the Macintosh HD and the Macintosh data”

You are here erasing the contents of that storage; the storage within your MacBook Air.

Everything on that storage will be gone. All files. All documents. All apps.

This erasure also in a way that correctly prepares the storage for a wholly new installation of macOS Catalina.

You are not deleting it. You are reformatting it. It is not possible to delete a disk, which is a physical device.

APFS, as was mentioned...

But you’ve got this working.

Now get your backups set up.

See: How to reinstall macOS from macOS Recovery - Apple Support