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iMac 2011 cannot re-install OS 10.8

1rottenapple

1rottenapple

macrumors 601
Original poster
Apr 21, 2004
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I bought a used iMac 27in 2011 model. I previous owners reset the machine (yay), however, when I try to reinstall Mountain Lion OS 10.8, I can't get into the App Store to re-install the software, therefore I can't log into the system.

When I log into my iCloud account (it ask you for your Apple ID to install the OS), it says my "this item is temporarily available" (see screenshot). I tried multiple iCloud accounts but I can't log on. The wifi works.
 

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Is there a reason you want to install 10.8 Mountain Lion? The latest Mac OS for this Mac is Mac OS X 10.13 High Sierra.

If the previous owner ever installed Mac OS X 10.12.4 or later you should be able to hold down Option Command + R on boot to get High Sierra Internet Recovery.

If the system already has Mac OS X on it and you can boot into it, I would update it to the latest maybe starting with 10.10 then working your way up to 10.13. Once you are on 10.13 you could then boot to the recovery partition, wipe the hard drive and do a clean install. If you install the latest security updates the Boot Rom should be updated to the latest (if it has not been already).

Alternatively from another Mac you could download High Sierra (or an older Mac OS) from https://support.apple.com/en-gb/HT211683

You could then create a bootable USB to reinstall Mac OS X onto the machine.
 
Hmmm well that's the OS that pops up when I turn on the iMac. Let me see about your suggestions.
 
Ok so I restarted the iMac, when make the "dong sound" I hold command option R at the same time. The only Manu that pops up is:
 

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If you select Reinstall OS X which version does it try to install?
 
its showing 10.8... but I get that code that I stated in the first post.

Im trying to download a copy of high sierra but when the App Store opens it thinks I want to install it on my 2019 16 inch MacBook and prevents me from downloading.

How to download and install macOS – Apple Support (UK)

Download and install current or previous versions of the Mac operating system on compatible Mac computers.
support.apple.com support.apple.com
 
You could try changing the date in Terminal to an older date and see if it will install. The security certificate for older Mac OS has expired.

Alternatively Download an older OS from that webpage e.g. Yosemite and create a USB installer. To install it when booted off the USB you will need to adjust the date using the Terminal to a date when the certificate was still valid.
 
I just can't get a copy of 10.8 or high Sierra that will let me create a bootable copy. For example I downloaded the install OS X Mountain Lion.app but I am missing the folder to drag into the terminal to create a bootable copy.
 
Well try Yosemite or El Capitan or Sierra. You can download what's needed from the webpage I linked to above for those.
 
Download the 10.12 (Low Sierra) installer here:

How to download and install macOS - Apple Support

Download and install current or previous versions of the Mac operating system on compatible Mac computers.
support.apple.com support.apple.com

I think this downloads as a "pkg" file.
When you double-click the package, it launches and installs a copy of the installer app into your applications folder.
Then, you double-click on the installer app and "click on" from there.
 
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Fishrrman said:
Download the 10.12 (Low Sierra) installer here:

How to download and install macOS - Apple Support

Download and install current or previous versions of the Mac operating system on compatible Mac computers.
support.apple.com support.apple.com

I think this downloads as a "pkg" file.
When you double-click the package, it launches and installs a copy of the installer app into your applications folder.
Then, you double-click on the installer app and "click on" from there.
Click to expand...
ok let me try that thanks!
 
ok i downloaded it.

When I click on the file it opens an installOS.pkg.

I click the pkg. A screen pops up saying, "this package will run a program to determine if the software can be installed".

The issue is this in my 2019 MPB 16 and I need to make this pkg run on a imac 2011.

Also there is no "copy of the installer app into your applications folder". It doesn't show up... hmmmmm
 
OP:

OK, I have another suggestion, since you already have the pkg file.
I don't know if this will work, but it's up to you to try it to find out.

You'll need a USB flash drive that is 16gb or larger.
You could -try- 8gb if you have one, that might not work.

You'll need one of two applications.
Both are FREE to download and use.
They are:
- DiskMaker X
- Install Disk Creator.

Search for them and download the appropriate versions for Low Sierra (10.12).
I suggest you download BOTH, try one, if that doesn't work, try the other.

Erase the flash drive to Mac OS extended with journaling enabled, GUID partition format (using disk utility).

Then, try one of the apps first.
Double click and see if it will launch.
If it does, follow the instructions it gives you.
The part I'm not sure about:
Whether or not either of these apps will understand the "pkg" file and be able to "extract" the OS installer from within it.

But... you've got to try to find out.

Let us know.
 
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Ok I downloaded both of the files, disk maker x and install disk creator. I then downloaded Low Sierra. The DMG file for Low Sierra 10.12. is called installs.dmg. I double click the install disk and it creates a pkg file called installOS.pkg. When I double click the pkg file, it opens the "installer.app". It tries to install the pkg file on my 16 inch MacBook Pro 2019 model. I tried opening the file by using the diskmakerx this file cannot be used to create an OS X installation disk. When I try using the install disk creator app, it says :

The selected item does not appear to be a valid macOS Installer.
It is lacking the file "Contents/Resources/createinstallmedia"
 
Make sure you are trying to use the app not the dmg to create the bootable USB.
 
ok let me make a vid tomorrow I took a break trying to fix this. i also bought the mountain lion os from Apple so will see if i can make this work, then try apple os download.
 
Oh let me clarify. When I click the dmg, it creates an pkg file. That’s what I tried opening using the above apps. When that didn’t work I tried the dmg just to test it.
 
there's absolutely no need to use third-party applications to create a bootable macOS USB. I don't know why those recommendations keeps appearing.

The attached screenshot is from a recent 'Yosemite' Install.dmg file where the .pkg file is opened with Pacifist - I knew that the createinstallmedia file is in there. The program DiskMakerX is lying.

Use what Apple tells you, but remember that the syntax for creating the bootable USB key has changed over the course of more recent macOS releases.

Apple tells you all this.

Also, the drive name is probably hindering some installations too. Try getting rid of those symbols and call it something with letters instead. Like "Macintosh HD" for fun.
 

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1rottenapple said:
Oh let me clarify. When I click the dmg, it creates an pkg file. That’s what I tried opening using the above apps. When that didn’t work I tried the dmg just to test it.
Click to expand...
Try seeing if the time and date are correct. And try putting and Ethernet cable in to the Mac - Boot up with Command+Shift+R - I think that's the combination.

Read more about it all here: https://support.apple.com/en-us/HT201255

There is a solution to all this.. Extracting the macOS installation with Pacifist could be a last resort if you can't directly install using the .pkg file. Yosemite is too "old" I to install on my iMac, I wouldn't be able to install Yosemite anyway as my iMac came pre-installed with El Capitan.

We'll hopefully find a solution together.

edited to remove my claim that most recent macOS can fit onto a 8GB USB - that's not the case.
 
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I’ll try any solution close to sacrificing a bat 🦇 😂 I’ll check it out tonight. Thanks to everyone helping and giving suggestions 🙏🏽
 
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