There Was a Problem Installing Mac OS X (Lion)

I had a couple of MacBook Pro laptops grace my desk and I have been upgrading them to Mac OS X 10.7 (Lion). The first one (maybe eighteen months old) went through without a hitch but the second one (which is a few years old) had all manner of problems including reading my original DVD-RW that I had burnt using the DMG file from the Mac App Store. Another significant problem I encountered was after the initial installation, I kept encountering the error…

“There was a problem installing Mac OS X”.

Quite non-descript and quite unhelpful and even a format and subsequent reinstall didn’t fix the problem.

What I discovered was that the setup for Lion seems to store data in the PRAM (Parameter Random Access Memory) and if this data is corrupted or becomes stale it becomes necessary to reset it in order to undertake a successful installation.

So how is it done?

  1. Turn off the computer,
  2. Hold down “Command”, “Option”, “P” and “R” on the keyboard,
  3. Turn on the computer,
  4. Keep holding down the keys until the computer restarts itself again (maybe ten or fifteen seconds at most),
  5. Release the keys after the computer has restarted again.

From here you should be able to proceed with the installation of Lion with no further problems.


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  1. Thank you – this helped me

  2. finally it works. i couldn’t get through this error, bit now it works fine on my old MacBook Pro. thanks

    1. Glad to hear! It’s certainly one of the more obscure and frustrating problems encountered with an OS installation.

    • changyoung on September 7, 2011 at 01:34
    • Reply

    Oh my god! thank you!

  3. Thx for the tip !

    • Jo on September 20, 2011 at 13:13
    • Reply

    OMG! You are a life saver. Thank you.

    1. No worries 🙂

    • Elliot F on September 21, 2011 at 04:17
    • Reply

    The user had re-formatted his HD and couldn’t recover. Nothing else worked. 2 days. The recovery partition, Firewire target disk mode, DVD installer. After clearing the PRAM, installation is going now from a clean install DVD image.

    • Michael H on December 7, 2011 at 00:14
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    You ROCK! Didn’t know we had a “P” ram still. Thank you Soooooooo much

    1. My pleasure!

    • Martin on December 20, 2011 at 07:24
    • Reply

    Thank you so much.

    1. Glad to help 🙂

    • Chao on January 3, 2012 at 00:18
    • Reply

    Great tip, thanks.

    • gandalf on February 12, 2012 at 02:28
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    saved me, thank you very much!!!!

    • Dave Kemsley on February 18, 2012 at 18:29
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    There’s one more step to do this for those who have the firmware password turned on: turn it off.

    You can’t reset PRAM/NVRAM if the firmware is password protected.

    1. Actually PRAM resets the Firmware password, you just have to either change a ram stick or temporarily remove it then reset the PRAM.

    • Isra V on February 22, 2012 at 13:04
    • Reply

    Thanks for your help…Regards.

    • Boris on May 1, 2012 at 08:36
    • Reply

    Thanx a lot!!!! Respect!)))

  4. Thanks man!

    • Marc on June 4, 2012 at 05:20
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    Mines not working 🙁 have been having problems for a while so decided to erase the disk and do a reinstall. Only problem is I didn’t back up lion to an external drive. When I try and reset the PRAM it he machine is not restarting itself and I just end up back at the same screen with the same message 🙁 any ideas more than welcome

    1. That is odd. Let me think about this and get back to you.

  5. Awsome! You have helped me out (after 3 hours of reinstalling boot drives etc) – Big up man Go buy yourself a beer from me. 🙂

    1. No worries at all 🙂

    • James on September 23, 2012 at 06:18
    • Reply

    Dude THANK YOU! I’ve seriously been trying for a day to figure it out. Used two different hard drives and STILL was getting an error until resetting the PRAM. You’re awesome

    1. It is such an annoying issue when you don’t know what is going on! Glad to hear you’re back up and running 🙂

    • Magid on December 11, 2012 at 06:30
    • Reply

    Tried to up grade my mac book pro by installing osx mountain Lion ,keep receiving massage telling me the hard drive is damaged and cant be repaired, tried disc utilities trying to repair it doesn’t allow me tried to reboot using safe mood doesn’t work I don’t have extrnal device to reboot from can u help please
    Many thanks

    1. It sounds like the drive itself might be on the way out but I note @ that someone used Alsoft DiskWarrior which did the trick for them to at least roll back to their prior version of Mac OS X. Seems as if Mountain Lion can damage the partition information but DiskWarrior can correct that bungle.

      Your mileage may vary and I’ve not used this myself but worth a shot before seeing an Apple Genius (if your Mac is under warranty) or buying a replacement drive.

    • Toshlad on January 22, 2013 at 05:44
    • Reply

    My daughters MacBook HDD failed. I put an old drive in and it nearly installed but then the install hung. I thought the replacement drive might be suspect so went and bought a new HDD. Then I got the error above. I was nearly at my wits end and my daughter had given up hope of having her mac back. You saved the day. YOU ROCK!!!!! Thank you for your help.

    1. My pleasure – happy computing! 🙂

    • mustafa on February 14, 2013 at 21:23
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    thnx vere much bro

    1. No worries 🙂

    • Kyle on February 19, 2013 at 20:00
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    Hey man, you really rocks. I mean i have been beating my self up about this problem. A friend of mine trusts me so much that he brought this problem and i could not fix it in 4 days. I read your article and within few seconds, T’adaaaaa….I’m good. Thanks so much and i hope i could follow you on twitter or so..BTW…big ups.

    1. It is a tricky problem but easy once you know how! If you want to follow me on Twitter my handle is @therealboydchan 🙂

    • Donny on February 20, 2013 at 09:47
    • Reply

    Thanks, that’s very helpful

    1. No worries 🙂

    • Reza Arian on March 4, 2013 at 20:05
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    Tanx-Tanx-Tanx-Tanx-Tanx-Tanx-Tanx-Tanx-Tanx-Tanx-Tanx-Tanx- 😉

    • Steve Job on March 7, 2013 at 20:30
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    Oh boy, for 3 days and now it’s that simple. Thanks!

    1. No worries 😉

    • Nantanut from BANGKOK on October 29, 2013 at 01:17
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    Thank you so much you save me Thank thank you

    • Mussa on March 29, 2018 at 23:59
    • Reply

    My problem was solved by this
    Thank you very much

  6. Muito obrigado mesmo! Eu ja estava achando que o macbook tinha ido embora! Você foi genial! Muito obrigado aqui do Brasil!!!

    • Peter M on January 6, 2019 at 08:30
    • Reply

    Thank you! I am refurbishing an Early 2011 MacBook Pro and couldn’t have succeeded without this info!

  1. […] Oh well, nothing the Googletron couldn’t take care of. […]

  2. […] Anyway, if the above hasn’t worked you can also try resetting the PRAM on your Mac by following these instructions. […]

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