OS X could not be installed on your computer

This thread saved me.

I have been trying to diagnose my computer issue for a month and a half. Mine started when my virtual windows drive for Parallels came to a screeching halt but my mac ran fine. I re-installed parallels about 20 times and even went and bought a new windows disk for over $100. That didn't work.

I decided to create a USB install disk of yosemite and completely re-install my operating system. Was getting errors and couldn't install. You guys mentioned memory and it all made sense. I put some third party ram in my mac a few years back. I popped it out and whammo installed yosemite right up.

All this time all I had to do was open my port and pop out the bad ram. Would of took 2 minutes instead of countless hours. Unreal.

Ran into this problem as well. I had four sticks of Crucial RAM in a 2011 iMac. I removed two sticks and still had the problem. I found two sticks of Hynix RAM and put them in and the Yosemite install then progressed.

Its just frustrating that the cause of failure to install was not ever indicated — so much time wasted.

Actually I found out this was not the issue. For some reason yosemite did work when I popped out the ram for the install but I still ran into the same issue with parallels and was running so slow. I had to type a small terminal command to clear my Nvram and it worked like a charm after that. I have no idea why I could not install yosemite without popping out the ram and I thought that was going to solve my parallels problem but it didn't. Again, small terminal command to clear the Nvram and back to new again.

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

This is the error I was getting trying to do a fresh install of Yosemite on a mid 2011 imac.

This thread convinced me to focus on RAM. I removed one of the two factory sticks, no luck. Put him back in and removed the other one, SUCCESS.

One of the two original RAM sticks must have failed the Yosemite hardware test. Now that Yosemite is successfully reinstalled, I may try putting it back in, but I'll probably buy new. Thanks everyone.

Many in this thread have attributed this problem to third party memory. I ran into this same problem with the memory that Apple shipped with my computer from day zero. I have a 2010 Apple Mac Book Pro 17-inch 266 GHz with 8 gigs of RAM. Apple shipped the computer to me with 4 gig Samsung memory. I didn't have any problems with the computer until I attempted to upgrade to Yosimite. Regardless of if I did an upgrade installation or a clean installation the problem occurred. When I installed Mavericks things worked fine.

If I put the computer in Target Disk mode it was possible to install Yosimite from a different computer. But I could not perform any updates or app installations. After I installed third party memory all of the problems went away and I had a functional stable computer again.

My ram was also Samsung 4GB original. Incidentally, after successfully installing Yosemite, I put the "bad" stick back in the computer and it works fine. I do plan on replacing it with new third party ram.

I have the same problem with the same model MPB retina 2012. 4mem error, ram is fix on board. I am helpless.

Actually, I was having this same exact error and tried many different ways to resolve it. Finally got it resolved it by:
Rebooting and using Command+R (Or "Windows Key"+R if using a Windows Keyboard) on boot up.
Going into Disk Utility and wiping my Mac drive (could something on there be interfering?)

Connecting to my wireless connection (it doesn't keep your connection info - no connection and it cannot download files again. It won't tell you that tho)

Installing Yosemite letting it re-download and re-install.

I have 4GB of RAM. 2GB original RAM that came w/ my Mac Mini (circa 2009) and 2GB Kingston I had bought to increase it to 4GB.

In my case this was not a RAM issue, but from what I see it gets pinned as the culprit for this error fairly often. I'm not so convinced this is the case most of the time.

Maybe this can help somebody... Seems as this is in fact a memory issue.

I have an iMAC late 2009 (yes it is old) and spend hours and hours getting Yosemite to work facing two different issues 1) an issue about the download being corrupted and 2) the issue about the essentials.pkg.

My iMAC has 2 x 2GB installed by Apple and NO 3rd part memory.

Sooo here is what I did, facing the iMAC trying to reboot and thus retry installing Yosemite over and over and over again...

Took out one memory block and retried. That failed.

Then I replaced the memory block left in the iMAC with the one I took out before and retried again. And now JUST NOW my iMAC is on Yosemite...

Thinking a bit more about the issue that lots of people (me included) experience with the Yosemite upgrade failing due to hardware problems I start wondering about Apples capabilities or wish to provide appropriate solutions. Not to mention the huge amount of data being lost due to a stupid bug that Apple could so easily avoid.

Why not:

1. NEVER EVER get the installation to a point of no return without doing the proper testing of the system; i.e. can Yosemite be installed on this system; if not then exit and offer a rollback option to current version of e.g. Mavericks
2. WHEN finding a hardware issue significant enough to basically brick ones system, then for GODS SAKE inform the user about the issue.

May I humbly suggest running the Hardware test already available in the system as part of the upgrade and BEFORE starting to mess around with changing system installations.

I am so pleased that I found this thread! Had some issues with my hard drive on my iMac mid 2010 and so wiped it and tired starting from scratch. Constant issues arised! Tried installing in every different way possible, nothing worked! So I bought a 500gb ssd Evo online and some extra RAM and have been again trying to install the OS with these in and still no joy. Pulled out the original RAM and left the new crucial sticks in and voila! installed first time. I have then put back in the original RAM and its recognised and seems fine! May you be blessed with ice-cream and prosecco for many years to come! Thanks a lot.

Like doublehardkent, I am so happy to have found this thread. I've spent days trying to get Yosemite to install. Even spent hours at the Genius Bar and they had no idea how to help. All that could have been avoided if I had found this thread earlier.

Basically, I had two third party RAM upgrades on my MacBook Pro (2009). I took one of them out to see if it was faulty and bam, Yosemite installed without issues. I didn't even have the original MAC RAM, but luckily it worked.

Thanks all!

Like doublehardkent and karlby I am so happy to have found this thread.

I spent hours trying to clean-install Yosemite on my Mac mini Late 2012 after having to wipe it clean because it wouldn't start up anymore (might have been due to a faulty RAM to begin with). Who would have thought re-installing the original RAM that came with the Mac mini would do the trick.

Thank you guys.

I have the same issue, however I have a macbook pro retina! The memory is on the main board there, so there is not much I can do with replacing memory... I've been on this the whole evening and no idea what to do here...