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  1. Hi. I am trying to reinstall OS X Yosemite in an old MacBook that I just erased the HD so I could give the MacBook to a kid in my neighborhood.
    I fallow all the instructions above, all of them, and I still get : “an error occurred while preparing the installation try running this application again”
    And that is it!
    Wondering if you can give any other advice?!

  2. Thank you soooo much Luis, I don’t have any idea how to fix it and just reading your simple solution and it work’s.. God bless you.thanks👏🏻👏🏻👏🏻👏🏻

  3. This is still happening in Catalina? Does anyone know what is causing this? After having this issue in the MacOs 10.15.2 update, I repartitioned and erased the hard drive and started over. 10.15.3 updated OK. 10.15.4 caused this same problem. Had to boot with cmd R and reinstall MacOs. Now, it works, but it shouldn’t be this hard with a Mac.

  4. Thank you so much, this helped bring an old Mac of ours back to life so that I could play Minecraft with my brother. (I know, I’m just kid)

  5. Safe mode startup succeeded but the next time the (normal) boot ended as before, with the infamous “couldn’t complete” message.
    I followed Luis’ hint then. Actually on my High Sierra macbook it was clicking “apple logo -> startup disk” and then just confirming already selected macos system disk (the only choice). Thanks, Luis.
    Just of curiosity, I wonder how one could follow the “combo update” advice on a computer that won’t boot?
    regards, Michal

  6. Thank you!! I freaked out when, after a usual update, l got error codes and l coukd not get my computer to start up. Your various suggestions got me back to my work, being able to answer clients based on the info in my office, aka macbook pro.

  7. Thank you so much! Restarting from the installation disk worked. I tried all the propositions above and started to be desperate.

    So relieved

  8. Thank you….thank you….thank you! I was so happy to find your list of possible solutions and I was even happier when the first one (safe mode) worked.

  9. Thank you! It returned to normal immediatley after the safe boot- I’m a graphic design student & had no idea if my art files were in jeopardy or not, haha thankfully they were sound 🙂

  10. just close the white window where you see all the written stuff and go up to the bar where the apple logo is. go to “installation” and from there go to either the first or second option (don’t remember which it was) to re-select your Macintosh drive – click on the drive so it is highlighted and then click “restart” so your computer can restart with that drive. Should work then!

      1. Thank you Luis! After trying everything else I tried your suggestion and it worked! Much appreciated!

    1. Thank you so much this worked really well- I have a project due in a few hours and I was scared I wasn’t going to be able to turn it in. Thanks 🙏

    2. Thanks Luis! Worked for me too.

      This has happened twice on my work iMac in the past two months. Is there any way to permanently correct this issue so it doesn’t arise again?

      Any help would be greatly appreciated.

      Kate 🙂

    3. Every time i update high Sierra (4 x so far) it breaks my mac so i have to do this long winded shitty fix. Ugh mac sucks as much as windows now

    4. Luis! Thank you so much! I fought with this computer since last night and your suggestion is what saved me!

  11. So when none of that works it is time to test the partion of the volume being used as startup. This becomes critical if you are changing file systems as High Sierra introduced. Techtool Pro provides a partition test and repair function wbich will correct the error.

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