Mac Installer: An error occurred while preparing to install.

If you want to reinstall macOS on an Apple Mac, it can happen that this error message throws a spanner in the works: An error occurred while preparing to install. Try running the program again. – But it is no reason to despair. The error, which is not further named in the message, can be found quickly and can also be rectified without too much effort. In this guide I'll show you how to do it. 

An error occurred while preparing to install. Try running the program again. – This error message in the Mac Installer ensures that macOS cannot be installed. You can find and fix the error on Mac, iMac and MacBook via
terminal in recovery mode.” width=”1024″ height=”484″ /> An error occurred while preparing to install. Try running the program again. – This error message in the Mac Installer ensures that macOS cannot be installed. You can find and fix the error on Mac, iMac and MacBook using the terminal in recovery mode.

Common reason for "An error occurred while preparing to install..."

Probably the most common reason for the warning "An error occurred while preparing the installation. Try running the program again.” is an incorrect system time. If the time in the Apple Mac has been adjusted by resetting the computer, replacing the system hard drive or some other measure, you can easily change it to the current date and time values.

Start Mac in recovery mode

If you hold down the key combination Command+R (or cmd+R or ⌘+R) when starting the Apple Mac, you will enter Recovery Mode. You can find details about it in this post. If that worked, you will find, among other things, the menu bar in which you can Utilities the point Port selects.

Get and set Mac system time in Terminal

To get the Mac system time, enter the command in the terminal data and press the Enter key. Now you can see whether the current date is correct with the day of the week, day, month, year and time. If it doesn't match the current date, issue the date command again, but this time with a string representing the current date.

It works like this: month-day-hours-minutes-year - with two digits for each value. For September 3, 2019 at 11:30 am, the command would look like this:

dates 0903113019

You confirm the whole thing again with Enter. Then you can close the terminal and try installing macOS again. The error message should not appear again, but the loading of the operating system onto the Mac, iMac or MacBook hard drive should run smoothly.

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15 Response to "Mac Installer: There was an error preparing to install."

  1. A thousand thanks ... exactly the "Date" topic made me despair with the old Mac for over a year ... now it's working again!!!

    1. Hello Dominik! I'm sorry. The guide doesn't seem to cover all the causes of this error message. If you find out anything else that has helped you, I'd love to add it here in the article.

  2. Hi, thanks in advance for the date but now my next problem is my mac is from 2009 OS X Yosemite, when I install it it shows me that the article is temporarily unavailable, does anyone know what I can do now?

    1. Hello Jan! Try starting the internet recovery with the keys Command + ALT + R on reboot. Then the Mac should actually install the latest system that is good for your Mac. Alternatively, you can also try Command + Shift + ALT + R like I did here in the post have described. This installs the system the Mac came with.

  3. Hi,
    I'm trying to recover an iMac Mid 2011 21,5″ that has now got an SSD because the old HDD has given up via the Internet.
    I can also select the SSD, it then starts with completely confused time information (which also constantly jumps back and forth) until it aborts with the error message: "Additional components required for the installation of Mac OS X could not be loaded"
    I'm doing the whole thing for a friend of my daughter's and I'm not very fond of apples.
    Since I can't and don't want to invest too much time, is there a quick & dirty method?

    1. Hello Falconix! I had the same thing with me 2-3 days ago. I couldn't do anything with the Internet restore because this message always came up with the missing components. The solution for me: I made myself an El Capitan boot stick like this described here at Apple is. This made the installation easy. DiskMaker X, which should actually be able to create such boot sticks, also let me down. But the good news: El Capitan can still be downloaded using the link on the Apple site.

  4. Hallo,
    I exchanged the defective HD in a MacBook Pro from 2012 for an SSD. There also the same error. Changing the date doesn't help, UTC is also displayed. Is this a problem?

    Activate partition and enter password: can you explain that in more detail? Do you have to enter or assign one?

    1. Phew… which macOS do you want to install? Right off the bat I don't know why the date doesn't help... actually it should. The one with the password should be the admin password the Mac will ask you for.

  5. “The instructions do not appear to cover all causes of this error message”

    Seemingly? No, it apparently doesn't cover all causes (almost the opposite meaning)!

    1. “Other synonyms for apparent are: only in appearance, pretended, supposedly, ostensibly, not in reality.
      Other synonyms for apparently are: apparently, probably, possibly, probably.”
      → So maybe the author intentionally didn't list all the causes. Then “apparently” fits. ;-)

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