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El Capitan installation failed (error related to essentials.pkg)

I have a late 2012 27" iMac which was running Yosemite.


Today, when I tried to upgrade to El Capitan I repeatedly get the message:


OS X could not be installed on your computer

An error occurred while extracting files from the package "Essentials.pkg".

Quit the installer to restart your computer and try again.


I have tried repeatedly and keep getting the same error. Googling indicated that it may be a problem with non-Apple-memory -- I had 32 GB Crucial RAM -- so I replaced it with the RAM modules that originally came with the iMac but I ended up with the same error message.


How can I see details about what this error is? Should I go back to Yosemite (I do have up-to-date Time Machine Backups)? Any suggested fixes?

iMac (27-inch, Late 2012), OS X Yosemite (10.10.3)

Posted on Sep 30, 2015 12:31 PM

Reply
59 replies

Sep 30, 2015 5:31 PM in response to Sanjaya Kumar

Please try again after taking each of the following steps that you haven't already taken.

Step 1

Reset your computer’s PRAM.

Step 2

If your model has user-replaceable memory, and you've upgraded the memory modules, reinstall the original memory and see whether there's any improvement. Be careful not to touch the gold contacts. Clean them with a mild solvent such as rubbing alcohol. Aftermarket memory must exactly match the technical specifications of the machine.

Step 3

Back up all data to at least two different storage devices, if you haven't already done so. One backup is not enough to be safe. The backups can be made with Time Machine or with Disk Utility. Preferably both.

Erase and install OS X. This operation will destroy all data on the startup volume, so you had be better be sure of the backups.

Step 4

Make a "Genius" appointment at an Apple Store, or go to another authorized service provider to have the machine tested.

Sep 30, 2015 5:39 PM in response to Linc Davis

Hi Linc,


My problem was resolved by re-downloading El Capitan.


This morning I was perhaps one of the first few people to download El Capitan from the app store. (I had searched for "El Capitan" on the app search bar and when I first clicked the result it said "not available" but started downloading on the second click). Being an early bird, I suspect I downloaded an incomplete copy and got stuck in the re-install loop.


The AppleCare rep's suggestion to reinstall using Cmd-R -- which also had been suggested by others on this thread -- and that did the trick.


Also, that reminds me -- I need to put back the Crucial RAM now that my issue is resolved.

El Capitan installation failed (error related to essentials.pkg)

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