An Error Occurred While Preparing The Installation Try Running This Application Again - MacBook Air 13

This is really annoying. But, after trying countless ways, I finally found one that resolved the macOS Sierra installation problem 100% (and without the need to create a bootable disk via USB).

The author suggests three alternatives - I used the third and it worked on the first try. Follow the instructions carefully and you will probably be successful too. The author generously created a very easy way to follow the instructions even if you don't have a 2nd Mac.

Here is the link to the original article. To make things easier, I'll reproduce the process that worked for me. I hope it works out for you too!

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At the main macOS Sierra menu, click on the Menu Bar and select the Terminal.app

Run this command in Terminal

curl -L https://archive.org/download/sierraurl/sierra.txt

This will give you a full list of instructions and commands on your screen. You can copy and paste directly into Terminal to avoid mistakes.

Change the directory to Macintosh HD

cd /Volumes/Macintosh\ HD

Download the macOS Sierra 10.12.6 InstallOS.dmg from Apple.com using curl. Note this is a 4.7GB file and might take a while or fail. If it fails run it again.

curl http://updates-http.cdn-apple.com/2019/cert/061-39476-20191023-48f365f4-0015-4c41-9f44-39d3d2aca067/InstallOS.dmg -o InstallOS.dmg

We need to mount the InstallOS.dmg

hdiutil attach InstallOS.dmg

Now we need to install the “Install macOS Sierra.app” from the InstallOS.dmg to Macintosh HD volume

installer -pkg /Volumes/Install\ macOS/InstallOS.pkg -target /Volumes/Macintosh\ HD

The Install macOS Sierra.app is now in the /Volumes/Macintosh\ HD/Applications folder. We can now start the Sierra installer

/Volumes/Macintosh\ HD/Applications/Install\ macOS\ Sierra.app/Contents/MacOS/Installassistant_springboard

In a few seconds the Sierra installer will start BEHIND the terminal window.

If you don’t see it make the terminal window but DON’T close it as it will stop the installer.

Done. Now step through the installer you are good to go now!

(Author: Mr.Macintosh)

Have you tried this yet?

Start up from macOS Recovery

Option-⌘-R

Upgrade to the latest macOS compatible with your Mac.

APFS won't work for Sierra, Sierra needs MacOS Extended Journaled. High Sierra won't work for APFS on earlier Macs.

What has often worked for others is to use this Restore Method instead of CMD+r keys...

Option-⌘-R

Upgrade to the latest macOS compatible with your Mac.

https://discussions.apple.com/thread/254793247?answerId=258936149022#258936149022

https://discussions.apple.com/thread/254872290?answerId=259072534022#259072534022

I was having the same issue on my iMac 2017. What finally worked is restarting with Option-CMD-R, this boots into Internet Recovery Mode with the newest OSX available that is compatible for the machine. I had to go into Disk Utility to name and partition the hard drive, then it offered OS Venture to install and it ran right to the end.

Trying to install Sierra was the issue. Try Option -CMD-R and see what works for your machine. Good luck!

hi I have a same problem and can not do it myself u can help me on instagram/mail or something plss?

(my instagram is *Daniel_prts* thank u )

If you want to do less steps, TLDR; Sierra installer is not working causing issues on newer macs.

Don’t use the Sierra installer, it’s broken, use Internet Recovery by booting your Mac with CMD+Option+R . This should boot you into a Monterey installer which will work.

Thank me later

1. Start up from macOS Recovery

Option-⌘-R

Upgrade to the latest macOS compatible with your Mac.

What format is the drive?

APFS won't work for Sierra, Sierra needs MacOS Extended Journaled. High Sierra won't work for APFS on earlier Macs.

What has often worked for others is to use this Restore Method instead of CMD+r keys...

Option-⌘-R

Upgrade to the latest macOS compatible with your Mac.

https://discussions.apple.com/thread/254793247?answerId=258936149022#258936149022

Clean Install of High Sierra: Multiple Fa… - Apple Community

An Error Occurred While Preparing The Ins… - Apple Community

Thanks to Clo3y…

https://apple.stackexchange.com/questions/309399/how-can-i-download-an-older-version-of-os-x-macos

Thank you soo much. I highly appreciate the help you have done to us. I tried for 2 days and still didn't work until you gave me the answer. The version worked soo well. I am 100000% out of 100% sure that this method will work. I tried it in my 27 inch iMac. I hope it works for all other macs. May the Triple Gem bless you!!!!!!

Sincerely,

A dude who tried to reinstall macOS...

Great news my friend, take care! :)

I get the same error message! I can't complete installation which renders my computer useless.

👍