MacBook air

Instructions on a New Install:

A. Create a Time Machine First (If an applicable option):

Create a Time Machine Backup of your Mac, that way you can have something to restore your Mac from, should anything go wrong with the reinstall, and need to migrate it all back. Use an External Hard Drive at least 1.5 times the size of the Internal Hard Drive. Take a photo of the app you have installed. Skip this if no concern for losing data.

B. Install the High Sierra Anew:

I. Create a USB Bootable Installer:

1. Go Here: How to Create a Bootable Installer for macOS - Apple Support
2. Use a Separate Mac: to create this.

then...

II. Erase the Hard Drive:

1. Boot: into Recovery Mode: Hold Down [Command + R] upon boot
2. Select: Disk Utility
3. Erase: the all volumes listed

then...

III. Install From USB Bootable Installer:

1. Plug in: The USB Bootable Installer
2. Hold Down: Option upon to boot into Startup Manager
3. Select: the USB Bootable Installer for the Startup Drive
4. Proceed: from there as necessary with the Install

C. Once the macOS is Installed - Reinstall the Apps...

I. Create a Second Time Machine First:

With a new clean install, create a Time Machine Backup of your Mac.

then...

II. Use Migration Assistant:

1. Go Here: How to Move your Content to a New Mac - Apple Support
2. Scroll to: Use Migration Assistant
3. Proceed from there as necessary

then...

III. Update Manually:

1. Contact: the Developer for the license, informing them of a failed install
2. Update: the installed software to 64bit (except for the macOS to upgrade)
3. Proceed from there as necessary

then...

IV. Create a Third Time Machine:

With a final install of updated apps, create a Time Machine Backup of your Mac.

Penelope_Hynes Said:

"MacBook air: My computer crashed recently so it’s super slow and unbearable to use, I was suggested to reboot MacOS Catalina with Mojave but my Mojave gbs are full how do I empty it if I can’t log on to the computer because it’s so slow?"

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Have any Backups?:

If you have any backups of this Mac, then boot in to Recovery Mode, erase the Hard Drive, reinstall the macOS, and then import things to the new install through use of Migration Assistant.

You haven't really answered my questions.

Have you erased your mac.

Or does your mac still have macOS Catalina on it.

Your screenshot tells you that the hard drive capacity is 499.25GBs

The figure underneath 441.38GBs is free space, that is more than enough to install

an operating system on.

If you want to downgrade to macOS Mojave 10.14.6 then you will need to get a copy of the macOS Mojave full installer app.

Before doing anything make full backup of your mac.

Open Safari and click on this link, 

How to get old versions of macOS – Apple Support

Go to the Download OS section and click on macOS Mojave.

This will redirect you to the App Store Mojave download page

it should say Get or Download. This will download the Install macOS Mojave.app

to your downloads folder, it should be 6.2GBs in size.

Then you need to create a bootable USB flash drive installer.

Read the instructions here,

How to create a bootable installer for macOS – Apple Support (UK)

You then boot to the bootable installer by restarting your mac while

pressing and holding down the option/ alt key.

In a minute or so you will see the Boot Manager, select the USB press Return.

From the Utilities window select Disk Utility and press Continue.

Click View in the menubar and select Show All Devices.

Highlight the Disk called Apple SSD.... or similar.

Give the Disk a name.

Format: APFS.

Scheme: GUID Partition Map.

Click Erase.

When Done quit Disk Utility.

Click on Install OS press Continue.

Follow the onscreen prompts.

When you have Mojave installed you can then restore only your personal data

from the Users/<useraccount> folder on the backup you made prior to

erasing your mac.

Point # 2 - Are there any AntiVirus, Disk Cleaner, Optimizers, Un-installers, 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. The Built-in Security of Big Sur is all that is required.

Is " CleanMyMac " installed ? - strongly suggest removing it as per the Developers Instructions. Do not Drag and Drop to Trash as it will leave elements of it behind. And, do not install an Uninstaller App as they too tend to create bigger problems.

The screenshot shows you have 441.39GBs available on your drive.

That is plenty of space to install Mojave if that is what you are doing.

It is unclear from your post what the exact problem is.

If a mac crashes there should be no need to reinstall the OS

and absolutely no need to downgrade your mac to an older OS.

Computers crash from time to time, usually not a big problem.

If your mac was frequently crashing then that could be a problem

but reinstalling OS's is not usually the answer.

Can you tell me exactly what you have done since the crash.

Have you erased your mac and are now trying to install macOS Mojave.

Did you erase your mac correctly.

What method are you trying to install macOS Mojave.

Penelope_Hynes Said:

"MacBook air: it says I have 499.25GB so too much for the 441.38 just wondering how to downgrade"

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What to Try:

Erase the hard drive. And then install it anew. Import it from a backup. Need instructions for this?