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Tech Tip: ‘An Error Occurred While Preparing the Installation’ Fix

Having worked in Technical Support here at OWC for some time now, I have helped customers handle many different types of errors and problems that they have come across. Some such as, “The disk you inserted is not readable by this computer,” might have simple solutions like formatting the disk, and some are more difficult such as “My Mac keeps freezing. Help!”

Related: My Upgrades tool helps you get the most from your Mac

One error that customers often come across while upgrading their machines occurs during the re-installation of macOS or OS X, and it has a relatively simple fix.

Once booted into the recovery partition and after selecting “Reinstall OS X”, the “Eligibility Verification” window shows up. The error occurs as soon as you click “continue”. An unspecified error shows up which states “An Error occurred while preparing the installation. Try running this application again.” Upon doing so, the same exact error pops up. Nothing has been done to have this occur, so what exactly is going on?

Screenshot of "An Error occurred while preparing the installation" popup window

While this can be frustrating, something quite simple is going on in the background that needs to be addressed. One of the checks that occur during “Eligibility Verification” is to see what time the machine thinks it is. If the computer is reporting the wrong time, an error will occur.

While there is a simple fix, it does require using the Terminal to accomplish. Many users might be wary of the Terminal, feeling like something could break and that it’s something only hackers and System Administrators use. While this can be true, the Terminal can be your friend and help you to resolve quite a long list of issues that commonly occur. But with great power comes great responsibility. Terminal can be destructive if its abilities are improperly used. My recommendation for those that are wary of this wonderful tool is to copy/paste commands or to type them very carefully and to double-check what was typed before execution.

To fix the aforementioned “unspecified error”, follow the steps below:

  • First, click “OK” on the error window.
  • Then click on “Utilities”, then “Terminal”.
  • Once opened type in “date” without the quotes and hit enter. This will give you the computer’s current time and date.
  • To fix the date, type in the current date/time in the following format: “date mmddHHMMyyyy”. (mm = two-digit month, dd = two-digit day, HH = 24 hour, MM = minute, yyyy = 4 digit year) So if it is currently 10:46am, June 19, 2015, the command would look like: “date 061910462015”.
  • Once you have the current date/time inserted, you will then hit enter. You can double-check to see if it was set properly by using the “date” command once more, it should show the date/time you have just typed in (see image below).
  • Once the proper date and time are set on the computer. Exit the Terminal and run the OS X installer once more. This time it should go through without any errors! If it doesn’t, feel free to contact an OWC technician for further assistance.

Screenshot showing the terminal command to change the date on a mac


Looking to Downgrade from one OS to another? We have you covered!

More tech tips from OWC

Look for many more tech tips on macOS Yosemite, El Capitan, Sierra, High Sierra, Mojave and Catalina for your Mac or iDevice at the Rocket Yard!

OWC Robert J.
the authorOWC Robert J.
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  • I was having this very issue with the Mac pro and this was the only article I found that help my issue. Thank you

  • THANK YOU I’ve been finding a solution to upgrade my MBP 2011 from MacOS Lion and that popup shows up when the download gets interrupted.

  • Wow, got me past that point and was not expecting it. Thank you! Now dealing with “this item is temporarily unavailable”.

    • FYI the fix for the “this item is temporarily unavailable” screen after putting in my Apple ID was to put in my husbands, who’s computer it was. Although he was not the the original owner it still worked.

  • Robert, thanks for the date suggestion. I use that frequently to do other Mac OS installs. I tried the suggestion that you provided above. It did not work. I keep getting “An error occurred while preparing the installation try running this application again.”
    I’m trying to install Yosemite 10.10 from the install disk.
    Any suggestions?

    Thank you.

  • wow, after hours of trying to figure this out with bootable usbs, networks, internet restores, changing the time is what worked? Go figure, serves me right to think I could do it myself.

  • Good day

    Sorry to bother you. I have a MacBook propro running OS X Yosemite and version 10.10. 5

    It keeps giving me error messages when I try install softwares

    (installation error message An Error Occurred While Preparing the Installation)

  • Thank you so much I just fixed up a MacBook Pro for my girlfriend and I was trying to see if everything was working smoothly and this popped up. You’re a lifesaver

  • I did all of the following options above even when I set upped the time and date correctly and try reinstalling the mac OS Sierra and I’m stillllll getting the same error “an error occurred while preparing the installation. try running this application again” What do I do pleaseeeee help

  • Oh.. my… God… this really worked!!!! Thank you so much!!!! I thought this MacBook was doomed for good.

  • This worked perfect! Any idea why the mac wouldn’t get the time from the apple time servers? Seems strange.

  • Went all around the houses trying to resolve this and cant believe it took me till now to find the solution here!

    Still not decided if its positive/negative that it was so quick & simple.

    Thank you – My daughter now gets my Macbook!

    Do you have Patreon?

    • Thanks for asking, Carlos, but we don’t have a Patreon account. This blog is a free service to all of our readers, but you can support everything we do here at Rocket Yard by patronizing!

  • Its moments like these when I’ve no idea what to do to fix the problem that I find articles such as this, fix it in one fell swoop and then sit back and appreciate just how awesome the internet of information can be. thanks so much

    WORKED 100%

    • Totally agree. I’ve been on the phone with Apple for a long time today trying to fix this and this article fixed everything. I was skeptical it would work and it did!!!

  • Hi i have the issue of “this item is temporarily unavailable” please help.

  • THANK YOU!!!! I am pretty tech savvy and couldn’t figure out how to fix my old MacBook Pro that I couldn’t get in to…you are the ONLY site and article that helped…THANK YOU!!! This article rocks, as do you.

  • after signing in with my apple id. a message appears, “This item is temporarily unavailable. Try again later.” any ideas what that might be?

  • Does your machine have any non-Apple memory installed. The installer doesn’t seem to like that.

    • Years ago I upgraded memory to 4GB 800 MHz DDR2 SDRAM. I am not positive but it might be Crucial.

  • I have erased the hard drive on my iMac (Early 2008) and am trying to re-install El Capitan (10.11.6) that was running on it. It was acting up so decided a re-install was the best way to go. Followed the instructions and all went well until it it restarted. Message says” OS X could not be installed on your computer”, “No packages were eligible for install. Contact the software manufacturer for assistance. “Quite the installer restart your computer and try again.”


    • Were you able to successfully reinstall El Capitan on your iMac? I have an iMac early 2009 and am in same situation after erasing the HDD and trying to reinstalling El Capitan. I found another tip from internet that resolved the issue. Wanna know what it is?

  • Thank you so much!! This error was driving me crazy and your fix was easy to follow and resolved the problem straight away.

  • This was the solution for me after hours of trying to reinstall in various ways unsuccessfully. Genius! Thank you.

  • Wow!!! I would vote myself as THE happiest girl on the planet right now!!! Thank you SO much for sharing this little sliver of knowledge with us! I seriously cannot express my gratitude!

  • Holy crap. You are amazing and so helpful. Worked perfectly. Thank you!!!

  • Awesome !!
    By going to terminal and changing the date ….it worked like a charm

  • I reset the date to the day after I first purchased El Capitan – same result. Is there anything in a log file that would indicate what verification test is failing?

    • The original Apple memory in this MBP has been replaced. I found a note in a 2015 submission saying that OS X installation does not like non-Apple memory. This MBP will now run Ubuntu.

  • Thank you SO MUCH for these instructions! I was totally stuck with the error for an old Mac Air reset and this really worked!

  • Hello, i want to make clean installation.
    Delete everything and after that “Lion” OS can not install because have a problem.. and after 3 days searching and try to making smth i dont have a result.
    In last video when i see, tried to make bootable flash with mojave macOS, and everything is worked until i got there.
    Nothing works with this command “date”, try to change year, time.. everything and nothing.
    Now i am stuck here.
    Macbook Pro 15 – 2012

  • Hi
    I am in India and my brother sent over his old Mac Mini from the US, since he had barely used it. He had wiped it clean and said I should reinstall the OS. I followed the steps you have prescribed above in setting the date and time, but it still doesn’t work (it’s supposed to install Lion OS). The date and tine are showing up correct, but before the year it is showing PST,which I suppose is Pacific Standard Time. If that’s the case, how do I set it to IST – Indian Standard Time? If that is not the case, then how do I reinstall Lion? We don’t have Apple support available locally and hence I need to rely on online support forums or sites.
    Please help.
    Thank you.

  • Make sure if time says PST you set you set it to PST not local time.
    That worked great for me…

  • hi, thank you, can you tell me how to setup the time zone? should i do it when inputing time and date or before?

  • Did not work unfortunately.
    Question though….
    I am in New Zealand (NZT) and I set the time to UTC time, as UTC was the time zone listed.
    Should I have done this or set the time to NZT regardless?

  • date issue did not fix the problem. but i solved by format HDD using third party application, then use disk tools to format HDD.
    the start the re-installation. and it works fine.

  • Installing mac os x lion 10.7 on macbook pro A 1278 after erase all data. Message apear on screen this item is temporarily unavailable. Please try again later. This message appear after sign in apple id.

  • I tried this, but the error still persists when I try to install. Any further recommendations of a fix?

  • thank you – I bought a wiped macpro and needed to reinstall the OS X and this worked.

  • Thank you, I’ve watched numerous videos and gone to numerous different sites, and yours is the only one that addressed this issue that I came across. I greatly appreciate you writing this help.

  • My Mac book I want reinstalled but not working ,it’s shows like this ” An error occurred while preparing the installation. Try running this application what I need to do can u tell me this

  • Thank you! I was frustrated at continuing to experience this error and your simple fix has me on my way. I appreciate it.

  • Seemed to work but then just at the end of the installation process I get:

    A server with the specified hostname could not be found.

    Any suggestions gratefully received!

  • I was stuck trying to reinstall Lion onto an early MacBook Air – this worked like a charm. Thanks

  • Trying to install Mojave on an internal SSD from an external HDD running High Sierra on a Mac mini Late 2012, but still getting the same error after:
    Resetting time & date
    Reset SMC
    Reset PRAM
    Reformat SSD to Journaled HFS+
    Reformat SSD to APFS

    Anything else I can try?

  • I tried but once I pressed enter it came up with ‘command not found’
    and my terminal looks different to the example image.
    mine says ‘bash terminal’ instead of ‘OWC terminal’ and it has the word ‘bash’ written in the space instead of the words you provided in the image,
    what shall I do?

  • yes i tried this with the date it came up as commond not found
    have macbookpro on the terminal came up put the date came up jan2 22:38:35 PST2001
    then put in 06267382019 that when command not found

  • Thank you! This fix worked perfectly. Now only if I can figure out why I can’t log in to the App Store……

  • Great advice. Worked perfectly and not too difficult to do even for an amateur like me!!

  • Install OS X An error occurred while preparing the installation. Try running this application again. OK

  • when I did this I was able to switch time to my time , however it still says PDT , then I run the install and get the same error ….how do I switch to CDT

  • Brilliant! I don’t think I ever would have figured that out. Thank you!

  • WOW this worked! I have been trying to fix this for a year now and gave up decided to investigate and try one more time and it worked!!

    • I jinxed it, it asks for my apple ID and password and its saying “this item is temporarily unavailable”

  • Having similar issue but firmware time is correct? Trying to reinstall osx and getting same message? Any ideas?

  • Sensational. Worked exactly as you said it would. Thank you very much, I learned something tonight. Would be interesting to know why an incorrect date prevents the installation.

  • I faced this problem when installing El Capitan,10.11.6 from a local bootable usb to internal OWC SSD (yes,i put the SSD in first). I tried changing the date as in this article, and resetting with option + command + R + P and nothing helped.

  • Wow it worked. Its people like you that make having a Mac not a super huge headache.

  • Thank you so much! i tried everything and even contacted apple and i could not find the answer for months! thank you so much!!!

  • I have followed the directions but it’s still saying command is not found. Also terminal- bash – 80×24 at the top and -bash-3.2# in the box

    • I figured it out! It’s because you need a space between the word “date” and the numbers. I had typed them all together and kept getting the same message. Hope this helps!

    • Mine is showing the same thing. Bash- 80×40 at the top and -bash-3.2# in the box..

  • Thank You, Thank You, Thank You! I Cannot Thank you Enough! My laptop has been stuck at that restart screen for about 4 years now and I was finally able to turn it back on after changeing the date through the terminal! Thank you!

  • I have tried this and it starts to go through however once it asks me to log into the apple store i receive another error not allowing me to log in. any advice?

  • Dude, Thank you so so so much! I was on an hour call with Apple care and they couldn’t figure it out.

    Thank you!

    • a surprising thing happen while trying everything to solve my installation problems. I created a bootable disk to install sierra because changing the date did not work. After using the bootable disk, an error again occurred “an error occurred while preparing the installation…” Just as I was about to give up, I again saw instructions to reset NVRAM. I did not try it thinking that its another solution that will lead me nowhere but lo and behold, after resetting it and without inserting the bootable disk the high sierra was installed.

      • Hi thank you :) But when i come to install OS X El Capitan, and when i have to agree so i cant use the disk to instill it on, bc the disk dittent show up on my pc? What is the problem? Hope you can help :) Tanks!

  • This worked for my 2009 MacBook Pro, so strange how just changing the date and time affected installation

  • Thank you so much bro almost sold my laptop very informative kudos Time was set to 2001 lol wouldn’t connect to App Store this worked

  • Worked perfectly but after I agreed to terms of software license agreement and selected the main disk I sign in to the app store then it tells me “this item is unavailable” where do I go from there?

  • Followed your instructions perfectly but the installation won’t proceesame message is displayed again”Mac os x can’t be installed on this computer”
    please is there any other solution to this.

  • I get permission denied. I am an administrator level

    date: bind: Permission denied
    date: settimeofday (timeval): Operation not permitted

  • I would like to thank you sooooo much
    You’re an expert
    This article is the most useful article I have ever seen

  • Hi, After entering the date time etc it comes up with command not found, is this because I’m entering the information wrong?

  • I have one more question: how do I change TZ. The date command shows PST, but I’m on a diferent Time Zone. Thanks!

  • hey thank you it worked for me but i couldnt get to install because it said the disk is locked how can i unlock it? reason im trying to reinstall is because my computer wont boot fully

  • Set the current date and time – reset/remove the current MAC O/S on HD.
    have another IOS device to received the pin
    initiate a new download
    pin will arrive on new IOS device (like iPAD)
    adding the pin to the end of your password
    4 hours later you will have a new MAC O/S

    PS you r
    will need a valid AppleID user and password

  • Mine is still giving me this error, it comes up after i have agreed to terms and conditions just as the system is about to restart. I have OS X Mavericks, trying to install macOs High Sierra, I have other updates that are still pending though…I need help, so many applications need the software to be updated before they will work.

  • I was trying to update a Virtual Machine with Lion, and this solved it for me. I just had to change in the System Preferences. Thanks for sharing!

  • I was trying to update a Virtual Machine with Lion, and this solved it for me. I just had to change in the System Preferences. Thanks for sharing!

  • I went to the terminal and entered the date and time as directed. I then tried to install macOS Sierra. It worked fine until the 20 second mark. Then I get the following message: “An error occurred while preparing the installation. Try running this application again.” Multiple runs give me the same result. Do you have any ideas as to what else I can do to make this work?

  • I use High Sierra and i cannot see the utilites tab above..?? What to do please help urgent

  • I have no experience rebooting or reinstalling Mac OS and minimal knowledge when I’ve done on PC. I was getting my MBP mid 2010 ready for my buddy who bought my laptop so i figured i would clean it for him. Got stuck with this error and forsure thought it was ruined. This fixed my problem ! Thank you so much.

  • MacBookPro from 2009 and we’re writing the year 2018 .. and this trick worked! Thanks a lot.

  • The same error still appears after changing the date in terminal. Error comes at the last 12 seconds. Anyone able to help?

  • For everyone thats having problem installing because it cannot authorize your apple ID is because it still has old apple ID and password stored that had been used to register when buying the product. Best way around it is to download os x dmg file from getintopc but make sure u r downloading the OS thats been present in your macbook. Make a bootable USB out of it, press option when you turn it on and choose the bootable USB for Installation.
    Second way is delete everything including the recovery partition to use internet recover (Option + command + R)
    Hope it Helps.

  • Your advice was right on the mark for fixing my problem. It is important to leave a space after “date” then it worked BEAUTIFULLY! Thank you much. I am not a tecky but I persevered to solve the problem that was challenging me for over an hour. Good Job!!!

  • Now it says this item is temporarily unavailable. Please try again later. Now what? Oh my days!

  • I get to the point where it says to enter your icloud username a pass, once I do it says “Currently Unavailable” Any suggestions?

  • I’ve change the date via the terminal, but the same error still occurs.
    don’t know what to do anymore.
    any advise?

    • were you able to solve your problem? I am having the same problem. I fixed the date but still it is same

  • This tip about the time and date really saved the day! Just wanted to say thank you.

  • This worked for me, thank you. I suspected it was a date issue preventing Lion from installing and your step by step guide helped enormously.

    Trouble now is I still can’t install as it says my password is incorrect – despite being able to log in on another device with the password! Any tips on this please?

    • I had the same problem, log out of the account on the app store of the computer and then reset your account password, it worked for me

  • Yeah, been hearing for decades now how great macs are since they are so easy to use compared to those horrible windows machines… and then we have this nonsense. If it’s so great, why do I have to jerk around with setting the time in terminal just to get the damn OS to reinstall? Windows/Macintosh – same crap.

  • Wow after spending hours trying to get this done but to no avail .and then you happened and it stopped giving me the error..Thanks you the best

  • Thank you!!! This was exactly what I needed to resolve my issue. I appreciate this!

  • I’m having the same problem, but the thing is that my timezone is incorrect. It shows PST (Pacific Standard Time) instead of GMT.

    I tried changing through systemsetup -settimezone GMT, but it says command not found.

  • i get the messidge: date: settimeofday (timeval): Operation not permitted

    and than nothing happens, still the same error.

  • This did not work for me. I inserted what is said above and in return its stated: -bash: date 112323342017: command not found. Is there any other way to try to fix this?

  • Hi there- thanks for your instructions! however when i type in the stuff in terminal- it says ” bash: 112101462017: command not found”

    do you have any idea how to fix this? thanks so much really appreciate your help

    • Hannah,
      You need to have the word “date” in front of the numbers. For instance:

      date 112101462017

      Rather than just this:


      The reason being that the first word you type in is telling the terminal which program to call up (in this case the computer’s date and time tracking program called “date”), followed by a space mark which seperates the name of the program from what you want that program to do. In this case, the program expects that a string of numbers that comes after the name of the program is an instruction of what new date and time it should set itself to.
      Hope that helps!

  • If you have an internet connection, type “ntpdate -u” in the terminal to sync your time with Apple.

  • Also not working for me.

    It’s mentioned in a few of the replies… Can you elaborate any on the time zone? The output changes from PST to CDT in your screenshot, but no part of your command seemed to specify the change in zone. Mine starts in UTC and stays in UTC, so I’m unsure whether to input time formated locally or adjusted. The machine is/was set up as PST. (update: Neither works).

  • Thank you very much for solving that problem. I was stuck on that for 2 hours. Now it’s back to the original error when trying to upgrade from Sierra to High Sierra.

    “MacOS could not be installed on your computer. An error occurred while updating firmware. Quit the installer to restart your computer and try again.”

    It’s already running the latest EFI for a 2012 Mac Mini. I haven’t been able to boot into anything but Sierra Safe Mode, Sierra Recovery, or the High Sierra Installer on a USB stick I eventually flashed in Safe Mode for over 6 hours now. Ever since the first time I saw the above error.

    Now time to keep plugging away probably all night.

  • Holy Crap! You have no idea how many man hours I’ve put in to try and figure out whats going on with my mac and this worked, +1,000 internet points for you! thanks mate!!!

  • After I followed your steps it worked perfect but then I’m prompted to enter my Apple ID and password ,after I click sign in I get an error that says “this item is temporarily unavailable “ try again later

  • Command+option+r installs directly from the internet.

    Shift+option+r installs your original operating systems.

  • When I put in today’s date in the US format or UK format it comes up with ‘command not found’. Any ideas?
    It says:
    -bash: 091811092017: command not found

  • please am following your steps to reinstall my mac os but i cant find the “UTILITIES” for the “TERMAL”

  • Awesome!
    I can’t understand why I couldn’t find this on Apples web!
    Many thanks, you saved my day!

  • Thanks apple for letting me know that you cant intall because incorrect time. NOT!

  • I finally get installed the lion. Now I cannot upgrade to Capitain.
    It’s a mess everything happens with this machine…

    • I spoke with apple care support, and they told me since the macbook pro is from 2010 was shipped with snow leopard will be the only solution to restore somehow the factory settings with a brand new HDD. So i’m looking for buying an snow dvd to make this true…

  • Hi it is not allowing me to put any number except zero et all in date… please help

  • Hi from Spain,

    please let me know, what about if I landing from a broken hdd and with the new one, (without having a backup for my macbook) I can’t access the terminal…
    I only have those:

    Restore From Time Machine (don’t have a backup )
    Install macOS

    Get help online

    Disk Utility

    How can I change the clock?

    Any help welcome!!!

  • OMG life saver, such a simple fix to this annoying problem I have been dealing with. THANKS SO MUCH

  • I tried couple of times but didn’t solve my problem! Every time after reboot the date goes back to updated PDT. I live in Toronto but don’t know why it gets PDT agai.,? I have activated Filevault before crash, could it be the reason?

    • Hi there. I too am in Eastern Standard Time. I merely adjusted for Pacific Time (if it’s 9pm Eastern, enter the time as 6pm Pacific…1800 hours). That did the trick for me. Best of luck to you.

  • I tried changing the date and time but I still get the message at the end of the install.

  • Good article and easy to follow. It saved me a trip to Apple store and saving some money as well!

  • OK this sounds super stupid but I’m trying to change the date in terminal but I can’t get a space between ‘date’ and ‘0519…’

    I’m pressing the space bar but nothing happens. It only types as ‘date0519… ‘

    Why can’t I get a space? Should I be pressing another button at the same time as the space bar? Am I missing something?

  • Hi, I changed the date/time but I still get the error msg right at the end of installation. Is there something I’m doing wrong ?

  • I get the , “this copy cannot be verified” error, change the time back to 2015, then it allows to start preparing installation.

    But then it gives the error that you have above .

    I’ve set the time right to the last second, it still gives errors, please help

  • Mate, You are a life saver!!

    Easy instructions, worked first go….

    Computer thought it was 2015. Thanks again

  • Seriously can’t thank you enough for this info! Saved me a trip into the busy Mac store! Thanks again!

  • Wow! Thank you so much. Ive been looking everywhere for a fix for months and this fixed it thanks!

  • This does work but I have run into a snag…the download throws up a warning saying “this item is temporarily unavailable. Try again later.” Is there a solution to this hurdle

  • Wow.. awesome thanks for such a simple solution.. Got frustrated after trying many times..!

  • Hi. Ive tried the date change and i still get the unexpected error message. Any ideas?

    • its not working for me either. Keeps prompting ‘command not found’

      have you managed to fix it yet?

      • I had this problem and then realised there was no space between date and the numbers, has worked fine now!

  • thanks worked great however now tell me the item is temporarily unavaiable

  • Thank you so much. Worked immediately after following your steps. I had a feeling it wouldn’t work but i tried it anyway and Ii was so relieved when it did! Now I just have to wait 14 hours for OS X Yosemite to install

  • Having a hard time breathing while reading this Robert?! You should, cause I just gave you the tightest most loving virtual hug your virtual body has ever felt. Oh, and you probably felt a virtual kiss on your cheek too, that was from me. Thanks so much, I was wracking my brains for months wondering why a clean install was sticking. I’ll drink two beers for us later. Sorry, virtual drinking is frowned upon since I don’t know your age . Cheers mate!!

  • This solved it, thanks!
    What confuses me is how a machine that is clever enough to offer to search and download software to run any printer you connect to it, on the other hand will download an entire operating system from the internet after being wiped clean, but then at the final hurdle an hour later cryptically say it cannot go on. Spend hours searching though bad leads and find this page that solves it. Defaulting to the Apple HQ time zone and then internally disputing it is kinda dumb! Apple programmers make some pretty basic mistakes. And the so called geniuses at Apple stores should be re-named something less. And the Apple support people should monitor the pages with problems that never seem to be solved. Rant over. :)

  • Robert, thank you. I have been trying to find a solution to this issue for months, including various trips to the genius bar. Your instructions were clear to understand and easy to follow. Thanks again!

    • I had this problem and then realised there was no space between date and the numbers, has worked fine now!

  • Worked, sort of. After signing into the app store it tells me, “This item is temporarily unavailable. Try again later.”

    Any ideas?

  • Hi I had the same error problem, but i dont have access to my utility folder. I have already formatted my drive and i am installing mac os x with a macbook pro. do i have a simple fix as well? Please help.

  • The ‘date’ is the main issue, but you may have to fudge the year when you reset the date. I just had to do a clean install of OS X Maverick on a new HD, and I kept getting an error msg about a possibly corrupt flash drive. I reset the date to 2015 through Terminal, and installation proceeded without a hitch… Once I was installed, I reset to the actual date…

  • i did the changes on terminal.. but still the same error massage killing me.. what can i do now??

    can anyone help me on this :(

  • I’m getting Illegal date format in terminal.
    “date 01018512017” is the command I’m using. Am I missing something?

  • Hi, I have done the above, but am still getting the ‘An error occurred while preparing the installation. Try running this application again’ message.

    Driving me crazy!!

  • Thank you so much for documenting this. I think you just saved a lot of headache and my Friday night.

  • Thanks a lot..i was stuck when i tried to install windows via bootcamp because i wrongly created a bootable disk…was unable to reinstall osx for about a month…thanks

  • Thank you so much!!!! I was chatting with an apple rep for like an hour and they couldn’t figure it out!!!

  • I can’t access utilities to get to terminal. My system is wiped so when I boot up to try and install I have to bypass by using command R. Any suggestions?

  • Excellent , it worked…but now i cant select the disk where it needs to be installed…
    it is showing only Recovery HD

  • Setting the date didn’t work, but I found out how to see details on the error: Window->Installer Log (Cmd-L). This shows me that “the volume ‘untitled’ is read only”. Exiting out and going into the Disk Utility->Disk->Info(button), I saw that Writable=No. I searched the web and found this article: that basically says my internal drive is malfunctioning, so it looks like I’m buying a new one. Hope this helps others

  • Well, I set the date and relaunched the installation. The error occured again. I checked the date. Its ok. What now?

  • Worked perfect thank you!!!! Bought second hand air book was stuck till I found this post your awesome!!!

  • Thank you for the instructions. I was able to reinstall after changing the date which was set incorrectly. I never would have thought the error was related to the date! Cheers!

  • You sir, are a dead set champion!!! Solved the issue that had me beating my head against a wall for a while.

  • This was exactly the problem I had and your suggested solution worked! Thank you a bunch!

  • Good Afternoon, thank you so very much… was exactly the problem…solved with your tip very much appreciate it.

  • I would just like to say thank you!! It worked great. Just got a MacBook Air ’14 for $240 through LetGo (kind of sketchy, I know) and it wouldn’t let me reset it, so I kind of thought it was goofed up. But you have provided a fix, so I thank you for your efforts.

  • Thanks so much for this info! Possibly for non-tech-savvy users, explain a little more about what to do when you say ” Exit the Terminal and run the OS X installer once more”. It was a little ambiguous for me :) Thanks champ!

  • It’s crazy how we miss the simple things such as the date! I was ready to replace memory chips and hard drive! Thanks a billion!

  • I was really concerned about this issue and after following this simple instruction finally worked. Thank you very much.

  • I filled out this information and the issue seems to persist. I typed in ‘date 072820262016’. The time sets and seems correct but when I try to run the reinstall it doesn’t work. The only thing I’m noticing is that it says PDT and I’m in central time. Any suggestions?

  • owc to the rescue, it was driving me nuts, hands down, thumps up for your incredible support

  • This was the best tech advice I’ve gotten in years. THANK YOU! You saved my bacon

  • I googled the error because I had no idea how to bypass it and this page came up and it absolutely worked. Thanks!

  • That saved me so much time!! Random errors are not fun and you, my new friend, have saved the day.

  • Hi I keep trying but it just says command not found and I’ve double checked the time was June 10 10:05 2016 I put 061010052016 is that correct

    • The command would need the word ‘date’ before the numbers like the screenshot depicts. Once that is added it will work.

  • Great – it worked! Thank you.
    I forgot to add date the first time and thought oh no.

  • Hi, I bought a used MacBook Pro from scrap dealer, it had no HDD, after putting a new HDD, I am not getting this same error message though I have followed the instructions step-by-step. Help

  • I followed all the instructions and still getting same error, then I tried this and worked well.
    Turn off mac
    On start up press and hold command,option and R then Mac will go into the internet recovery mode. when the loading is finished, ( I had attempted twice) you will be able to install OS X

  • What if, after checking it through terminal, the date is correct, but it still displays the error box?

    • This is my issue as well. I have the correct computer time, but I am still getting the “An error occurred while preparing the installation. Try running this application again.”

  • You guys have just been incredible throughout this whole learning process. Psyched!!! Thank you!!

  • The terminal won’t open in Yosemite 10.10 recovery,when I click on it, the wheel spins for 1-2 minutes, and then nothing. What do I do? help!

  • I’m having the same problem as @Adam, has anyone found any other way to solve this issue? I’m unable to reinstall El Capitan from recovery mode at all. It keeps giving me the same error message even if I’ve got the right date settings in terminal. Could it be an issue with the time zone?

  • I’m trying to reinstall El Capitan from recovery mode, because that’s all my Mac will boot in for now, and it keeps giving me this exact error message. I’ve checked the date, it’s correct. I have no idea what it’s deal is, but this has been going on for 2-3 days. I haven’t been able to use my Mac at all and I’m frustrated beyond belief. Please reply asap. Thanks in advance.

    • Regrettably not all unspecified errors are caused by the date being wrong. If the date is correct I highly recommend contacting Apple for further assistance.