This copy of the Install OS X Yosemite application can’t be verified. It may have been corrupted or tampered with during downloading.

If you are trying to use an installer you downloaded previously…

OS X installers downloaded prior to 14 February 2016 won’t work- See TidBITS article: Previously Downloaded OS X Installers No Longer Work [Added 02 Mar 2016]

Trying to update a client’s computer today. After downloading Yosemite installer it failed to run. It would start but fail with the following error:

This copy of the Install OS X Yosemite application can’t be verified. It may have been corrupted or tampered with during downloading.

First step was to download again. That failed. Tried downloading again. Failed. Started looking for help and found many suggestions that worked for some users. After trying reset date, repair permissions, repair drive, remove RAM and downloading multiple times, user purchased a USB thumb drive and we were able to create a bootable OS 10.10 Yosemite installer drive using the installer that failed to run.

  1. The Install Mac OS X must be in Applications.
  2. Format the USB drive as GUID in Disk Utility. 8GB or larger
  3. Name “Untitled”
  4. Paste the following into the Terminal
  5. Enter Password
  6. When the process is finished you will see Copy Complete. Done. (the process took about 30 min so be patient)
  7. Select the drive in System Preferences > Startup Disk to install.

Thanks to Dan Frakes for instructions on creating USB installer. For more details, see Dan’s blog:

[Added info: December 3, 2015] Check out the FAQs on DiskMaker X page for help with errors making a boot disk. DiskMaker X is a free app that many find useful in creating a bootable install disk. This can be very helpful if you are running El Capitan and want to install an older version of OS X like Yosemite on another drive.


75 thoughts on “This copy of the Install OS X Yosemite application can’t be verified. It may have been corrupted or tampered with during downloading.

  1. I got the same error.
    I have made a bootable USB-stick with OS X Yosemite.
    Then changes my hard drive into an SSD drive.
    Restarted with option key.
    Then in the menu chose “install OS X”
    But then the error appeared…
    Some say it is a time/date error, but I have no menu option to see or change the time.
    What to do?

  2. @DRS

    Thanks for mentioning the date issue. I totally forgot about that being a problem. I reset date and problem was fixed. Thanks!

  3. I did everything correctly, checked date and it was correct and still got error! Now what to do? I have no internal hardrive with an Operating System. Do I go to the Apple Store and ask for a bootable memory stick?

    • Can you boot from the Recovery drive?

      Boot into the Recovery Drive by holding down Command R when restarting. 
      Run Repair Drive and Repair Permissions using Disk Utility in Recovery.
      You might need to reinstall OS X. This process should not damage your data but it’s always advised that you backup first.

  4. I wish I had researched the error message and found this date solution earlier instead of needlessly making a second boot drive. I had just replaced the battery, so of course the date had reverted. Duh! All’s well that ends well. Thanks!

    • If you have a new blank drive you will have to use another drive that has OSX and the Yosemite installer to format and install Yosemite.

      Do you have access to another Mac? If no, you should be able to take it to an Apple Store and have them do the install.

  5. Was really wanting to bring an older Macbook Pro back to life from a USB drive and ran into this. Was thinking, “dang, well there goes that, enough time wasted” and ran into this article. Worked like a charm!

  6. I’m having this problem but neither solution works for me. If I boot from the USB drive after a very long wait I still get an error that says “This copy of the Install OS X Yosemite application can’t be verified. It may have been corrupted or tampered with during downloading.”

    As for fixing my system time as many in the comments advised, my system time is already correct.

    Also checked my DNS settings and tried on a different ISP (recommendations made in other places). None of those things has helped.

    Anybody else have another suggestion?

    • Try these two options then check time again.
      1) Reset the System Management Controller (SMC)

      Turn off your Mac
      Plug in your Mac power cord into the wall socket
      Hold down the Left Shift + Option + Control + Power Button, simultaneously, for about 10 seconds
      By doing the key presses listed above, your Mac won’t power on but the reset will be done
      Release all keys after about 10 seconds and turn on and run your Mac normally

      2) Reset PRAM

      Similar to resetting the SMC, you should periodically reset your computer’s PRAM. Here is the Apple Support Article for Yosemite –

      Turn off your Mac
      Press the power button
      Press Command + Option + P + R in combination, all together, before you see the initial startup screen
      Press and hold until your Mac restarts
      Release the keys when you hear the familiar startup chime/bong sound that your Mac makes when it starts up (you may hear it twice which means that the PRAM has been reset)
      Your PRAM reset should be complete

  7. Thanks for the suggestions and the detailed instruction. Unfortunately it didn’t help.

    So far here is everything I’ve tried, with the same result every time:

    I tried re-downloading. I tried rebooting. I verified the date. I checked the DNS. I verified the hard drive. I checked permissions. I repaired the hard drive. I tried installing from the App Store. I tried creating a Yosemite install disk and booting from that to install. I tried creating a new virgin admin account and installing from there. I reset the SMC. I reset the PRAM.

    Anything else I can try or is an OS upgrade never going to happen?

    Is there a way to try installing Mavericks and then upgrading to Yosemite? I don’t know where I’d get a Mavericks install though.

    • How much free space on your drive? Use Disk Utility to find this info.
      Do you have an external drive that is large enough to backup your data?

  8. Hello..

    I have IMAC was it upgraded last month with Yosemite , After upgrading it was hide some futures..such built in web cam, DVD Drive and external UBS drives Ect;; I was find in the web to fix them.. finally desired to clean re install Yosemite.. Created a usb thumb drive (Yosemite) erased HD and partitioned.. then try to install OS i got a error # 0 saying try again.. please help how to fix this.. appreciate your soonest replay on this..

    • If you still have the original partition, you can turn on the hidden features.

      It’s possible the USB drive you installed Yosemite installer was incorrectly done. Try booting into Recovery Drive and select Reinstall OS X.

      Boot into the Recovery Drive by holding down Command R when restarting. 

      Select Reinstall OS X.

  9. This copy of the Install OS X application can’t be verified. It may have been corrupted or tampered with during downloading.

    Read through the other entries and still no luck.

    My Mac was on Yosemite, but after upgrading from 10.6.8 I have had NOTHING but constant crashing of the browsers (Chrome, Safari, Firefox) which started after the Yosemite upgrade. That on top of very slow system performance led me to do a ‘fresh install’ of Yosemite.

    So I backed up the system using Time Machine, properly reformatted the thumb drive, created 2 partitions (32gb, 16gb each), went to the App Store, downloaded Yosemite and copied it onto the thumb drive, Untitled1. I then erased my hard drive and reformatted it properly to the /journaled option.

    I can boot from the thumb drive, but when I try to install Yosemite, get the error above. I have checked the machine date/time via Terminal – its fine (not 2001).

    Made zero progress after a day, so I booted from my Snow Leopard disk, went through all the updates to make sure it was the latest level available from Apple (10.6.8). So I’m back on SNOW LEOPARD (not reliant on the thumb drive I created earlier). I then downloaded “OSXUpd10.10.4.pkg” dated June 24, 2015 6:58 AM. 1.09gb.

    Issue: I tried to run this package and got ALERT: This update requires OS X version 10.10. So I can’t upgrade because I have to be on Yosemite first? So I mucked around with that for many hours and gave up trying to find a 10.10.0 or .1 version of frickin OSX anywhere on an Apple certified site.

    Next: I went to the Apps Store and RE-downloaded from a page that says OS X Yosemite which produced a file in Applications: osxupd10.10.4.dmg, last opened June 30, 2015 8:57am. In Apps there is a file, “Install OS X” which is dated 1:26am (which is when I downloaded it last night), 5.68gb.

    And I’m back to the same damn error message I started with when I tried the clean install of Yosemite.

    What I need to know is what is causing the error message, not endless rounds of guessing. Problem with the file/checksum? Possibly, but with 2 multiple-hour downloads at separate times using a fiber connection I’m not going to assume the file is corrupted. Something else is amiss.


    • The file 1.09gb was an updater not the full installer. The file that is 5.68GB is the full installer.

      How much free space on your internal drive?
      How much space is used?
      Is your external drive with Time Machine formatted as GUID? How much free space.

      I would do a clean install of Yosemite to an empty partition. However, you would need to be booted from a partition that contains the installer.

  10. Thank you so much to the detailed guide about the time fix with regards to this issue! It fixed my problem, no more errors! Yay!!

  11. I am having the same issue. I have also received the error message “This copy of the Install OS X El Capitan application can’t be verified. It may have been corrupted or tampered with during downloading”.

    I am sure my date is correct as I have checked that and I am able to do an upgrade from Yosimite to El Capitan with the downloaded image so I know the image is not corrupt.

    I also verified that internet connectivity is working and that DNS is working.
    I also did the SMC/PRAM reset.

    The funny thing here is that I am unable to do a clean install of Yosimite either using a previous image that did indeed work before on the same Mac.

    Luckily I have a time machine backup and I can get my OS restored but would love to get to a point where I can do a clean installation of El Capitan.

    Wonder if someone else could suggest some more steps to a possible solution.

    • 10.11.1 is due out soon. I would wait a few days after release and try again.

      BTW, you might want to make a small Yosemite partition to use Disk Utlity in the future. The new Disk Utility is horrible. If you ever want to partition a disk it’s much easier in Yosemite. I have a small 32GB partition with Yosemite. This allows me to use the old Disk Utility in the future.

  12. Pingback: Apple:Yosemite Installation Error – Apple Questions

  13. For those who have tried everything and still don’t find solution, here is aolution.Tthe installer actually has “valid from” and “valid until” dates. It means the installer is good to work between specified period of time. So you might not set date in terminal to current date, but set to some earlier date.

    In my situation, I had Yosemite installer downloaded from App Store last year (2015), and today (Feb 17, 2016) I was trying to clean install my macbook pro with that installer again. I had “This copy of the Install OS X Yosemite application can’t be verified. It may have been corrupted or tampered with during downloading.” error. I remember last year I was able to install with the same installer without any problem, so i just set date from terminal to Jan 01 2015, and it intalled without any problem. Hope this helps.

    Credits go to Russell, who commented this solution in this post: Thank for him)

  14. Thanks to Russell (and you, for posting here)! I was having the same problems as the others above and it was getting frustrating.

    My situation was slightly different – I tried a date close to when the file was created, but no luck. I didn’t get the error, but rather the “preparing to install…” flashed and I was taken back to the main startup disk window.

    I used the exact date the file was created and this did the trick.

    – – –
    My specs:
    iMac 20″ (mid 2007)

    upgrading from OS X 10.4 to 10.10

  15. Thanks for all the comments on here.
    I purchased an ex demo Mac mini that had been locked down and wanted to set it up with my Apple ID.
    Unable to do recovery due to password not known.
    I had an installer copy of Yosemite on my MacBook Pro so I built a bootable install usb stick.
    Erased the hard drive and off we go!
    All stop with the “time issue”.
    Putting the download date of the Yosemite file into date on terminal and off we go 😄
    Wonderful – Cheers chaps

    Kevin – Birmingham UK

  16. LOL

    Apple are getting even worse. here we have a manufacturer who dictates which hardware you can use, and spends millions ‘updating’ its operating system to regular new releases, it can’t blame third party vendors, yet it is getting unbelievably bad to install. < remainder of comment snipped>

  17. I received error when attempting to install off booted USB media:

    “This copy of the Install OS X Yosemite application can’t be verified. It may have been corrupted or tampered with during downloading.”

    I incorrectly had the USB drive Partition Map formatted as Master Boot Record, even though I had the VOLUME formatted as GUID, which didn’t work.

    I correctly erased the USB drive and formatted the Partition Map GUID THEN created a GUID volume, did the createinstallmedia command and works as intended.

    Problem was GUID volume on MBR Partition Map USB Drive. Make both GUID and it works.

  18. Same here. The USB stick didn’t work, but backdating the machine in the System Preferences worked perfectly. (I misread the dates on this post and backdated to 2013 instead of 2015. 😉

    FYI, the last “2 minutes” of the installation took well over an hour (we went out, so we don’t know how much longer) but it did finish.

  19. Thank you all tried everything else but
    setting the date of my Mac Mini back to the day after I downloaded Yosemite from the App Store (5th January 2015 ) got rid of the ” This copy of the install OSX Yosemite … corrupted …tampered with ..” and I had a working Yosemite boot drive inside 40 minutes

  20. Thanks for keeping this blog post around, it helped me find out about the expired certificate problem. After sifting through tons of google results all saying it was the date issue, this certainly helped. All the comments saying this is a waste of time and to just check your system date are ignoring the fact that their problem could just be a different cause from some of us. My date is correct and this was the only viable option.

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