Discuss: Special Report: Preparing for Mac OS X 10.4 (Tiger) Installation - Avoiding issues before and after updating Sign in to comment. Be respectful, keep it civil and stay on topic. Boot from Mac OS X installation disk / USB. Go to Utilities Terminal. Type date to check the current date and time. If it's incorrect, run following to fix the date and time: date mmddHHMMyyyy Where: mm - month, dd - day, HH - hour, MM - minute, yyyy - year; Clear NVRAM. Shut down the Mac. Preparing to install macOS Server. If you’re going to install macOS 10.14.4 on an existing computer and want a clean installation rather than an upgrade, use Disk Utility to erase the storage your volume is on. You can use Disk Utility when you begin installing. For instructions, search Mac Help for “Erase and reinstall macOS.”. Hello, I ran into the same issue while trying to factory-reset a Mac Mini 2012 with MacOS High Sierra from a USB key. The Mac Mini had a custom Fusion Drive with High Sierra on it, and was previously formatted with APFS.
Updating your Mac to the latest version of the macOS software is usually easy and straightforward. However, you may run into Mac update issues. A common installation error message that a lot of users are receiving is below:
“An error occurred while preparing the installation. Try running this application again.”
You may see this message when you want to install or reinstall an update or upgrade. This article explains how you can fix this problem.
See also: The macOS Installation Couldn’t Be Completed Error Fix
Here is how you can fix this problem:
Please try the following troubleshooting tips in order. After trying each step, test to see if you’ve fixed your issue.
1. Restart your Mac.
Simply restart your Mac to see if this fixes your problem.
2. Check the date and time.
Make sure that the date and time on your Mac are set correctly. Here is how you can check this:
- On your Mac, click System Preferences, then choose Date & Time. If your settings are not correct, update them. You may also want to check the “set date and time automatically” box to turn on the option to set date and time automatically.
- However, the option above may not work for you as you may not access System Preferences if your Mac stuck in the middle of a macOS update. Then you can use Terminal (Applications / Utilities) to update your date and time settings. Here is how:
- Turn off your Mac, you can do so by pressing and holding the power button.
- Turn on your Mac and immediately press and hold the Command (⌘)-R keys together. Keep holding these keys until you see the Apple logo or a spinning globe.
- Your Mac will start up from macOS Recovery. This may take time so be patient.
- Enter your password, if asked.
- You will see the “macOS Utilities” window.
- From the top menu, click Utilities and Terminal. This will open the Terminal window.
- In Termina, enter the following command and hit enter:
- date
- This will give you your computers time and date setting. Is that correct? If not, update it:
- If your Mac has an Internet connection, enter the following command and hit enter:
- ntpdate -u time.apple.com
- This will automatically update the setting. If you have no Internet connection, then you will have to manually update this setting:
- Enter the current date using this format: date mmddHHMMyy”. (mm = two-digit month, dd = two-digit day, HH = 24 hour, MM = minute, yy = 2 digit year) So if it is currently 11:46am, April 03, 2020, the command would look like: “date 0403114620”. So enter something like this:
- date 0403114620
- Again let’s doublecheck, enter the date command again to see if your Mac has the correct setting.
- Now exit Terminal and try again.
3. Try installing in Safe Mode.
- Turn off your Mac.
- Turn on your Mac and immediately press and hold the Shift key.
- Keep holding the Shift key until you see the Apple logo.
- Log in, you may have to log in a few times.
- Now your computer is in Safe Mode.
- Try updating your Mac now. Does it work?
- To exit Safe Mode, restart your Mac normally.
4. Use macOS Recovery.
- Turn off your Mac.
- Turn on your Mac and immediately press one of the keyboard combinations:
- Command (⌘)-R: This reinstalls the latest macOS version that was installed on your Mac.
- Option-⌘-R: This will update your Mac to the latest compatible macOS version.
- Shift-Option-⌘-R: This will install the macOS version that came with your Mac.
- Click Reinstall macOS and then Continue.
5. Use a combo update.
- Please note that you can use this method to update your Mac from a prior version of macOS within the same major release. For example, the macOS 10.15.4 combo update requires that macOS 10.15.0 or later is installed.
- Download the necessary macOS combo update from the Apple website.
- They are dmg files. Also, note that they are very large files.
- Double click the install the file. And then follow the onscreen instructions.
Hello,
Preparing For Installation Machine
I ran into the same issue while trying to factory-reset a Mac Mini 2012 with MacOS High Sierra from a USB key.
The Mac Mini had a custom Fusion Drive with High Sierra on it, and was previously formatted with APFS. The Fusion volume had been erased and reformatted with Journaled HFS+.
(@Apple technical staff: I hope this info helps you to improve the great products you are working on)
Just as in your case, the installation process went smoothly, up to the point where the installation disk contents where copied to the target volume, and Kaboom! : I got the screen as shown in Unable to install High Sierra - 'an error occurred while preparing the installation'
As you may know, APFS on Fusion drives is currently at Beta stage, so glitches are to be expected.
As stated before, however, the Fusion drive had previously been erased with Disk Utility and reformatted as 'Journaled MacOS Extended'.
Here is how I solved the issue:
- The issue came from the inability for the installer to unmount the Fusion drive before rebooting. I figured this out in Disk Utility as it could not unmount the drive to 'repair' it.
- So I used the instructions in the second part of this Apple documentation: APFS Fusion
- Open a Terminal window (in the Installer launch screen, it is under the 'Utilities' menu item.
- Look for the Unix names of your drives:
- #> diskutil list internal
- take note of which drive is the SSD, which is the HDD. In my case, it was as in the example from Apple: SSD was disk0, HDD was disk1.
- Force-unmount your target logical volume:
#> diskutil unmount force disk2s1
- Separately re-format each Drive of the previously-unmounted Fusion volume:
- #> diskutil eraseDisk JHFS+ SSD disk0
- #> diskutil eraseDisk JHFS+ HDD disk1
- Recreate a Fusion Drive:
#> diskutil cs create 'Macintosh HD' disk0 disk1
- Recreate a logical volume on it:
diskutil cs createVolume 'Macintosh HD' JHFS+ 'Macintosh HD' 100%
- Quit the Terminal application. You'll be taken back to the installer.
- Retry to install High Sierra. In my case the issue was completely solved.
Preparing For Installation Mac Os
Hope this helps, good luck!