27" iMac - cannot re-install OSX or Time Machine Backup

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27" iMac - cannot re-install OSX or Time Machine Backup

I have a 27" iMac that was the first of the slim unibody ones at the end of 2012, beginning of 2013. I think it is iMac13.2 model ID.

This morning it started acting weird, programs were freezing up and/or crashing, and I locked up on reboot a couple times.

Eventually I restarted in safe mode and updated software, as I had updated iTunes the other day, but was still on OSX 10.10.3 and had not updated to 10.10.4 so figured it might be related. That install hung up at the end and I had to reboot, but I had no options to reinstall that update again so i figured it was ok.

Of course at that point almost nothing was working. You could start up firefox or a game or something, but it would freeze and fail soon enough. Everything was failing.

So rebooted to disk recovery and I was told that I had a failure that required a fresh re-install. Ok, booted back up and backed up some files I did not want to lose, and then re-booted back into recovery mode.

My last time machine backup was last October, sad I know, because I don't like it running all the time as it slows the computer up when gaming and I kept forgetting to back it up manually. Still, I would have taken it. But it failed to restore from time machine. I get an error that reads "An error occurred while adding a recovery system to the destination disk. Restart your computer, and then try restoring again." But multiple attempts ended in the same message.

So I tried a fresh reinstall from OS X utilities, it's snow leopard still on this machine, but fine. It runs through its 30 minute install and then I get at the very end "An error occurred while preparing the install. Try again." I have tried like 3 times, no dice. I have looked it up and saw that it could have been related to a date/time thing, but checked the console and the date/time are correct. And I have tried it from both CMD-R and CMD-OPT-R.

I booted up the Mac Hardware Test, and it came out with no problems detected.

Any other thoughts?

Posted on Jul 5, 2015 4:22 PM

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Answer 1

Kappy

Level 10

361,741 points

Jul 5, 2015 4:33 PM in response to kennfusion

You cannot install Snow Leopard on that model. It requires at least Mountain Lion. Do this:

Install OS X Using Internet Recovery

Be sure you backup your files to an external drive or second internal drive because the following procedure will remove everything from the hard drive.

Boot to the Internet Recovery HD:

Restart the computer and after the chime press and hold down the COMMAND-OPTION- R keys until a globe appears on the screen. Wait patiently - 15-20 minutes - until the Recovery main menu appears.

Partition and Format the hard drive:

Select Disk Utility from the main menu and click on the Continue button.
After DU loads select your newly installed hard drive (this is the entry with the mfgr.'s ID and size) from the left side list. Click on the Partition tab in the DU main window.
Under the Volume Scheme heading set the number of partitions from the drop down menu to one. Click on the Options button, set the partition scheme to GUID then click on the OK button. Set the format type to Mac OS Extended (Journaled.) Click on the Partition button and wait until the process has completed. Quit DU and return to the main menu.

Reinstall OS X: Select Reinstall OS X and click on the Install button. Be sure to select the correct drive to use if you have more than one.

Note: You will need an active Internet connection. I suggest using Ethernet if possible because it is three times faster than wireless.

This should restore the version of OS X originally pre-installed on the computer.

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Answer 2

kennfusion Author

Level 1

15 points

Jul 5, 2015 4:42 PM in response to Kappy

Sorry, I meant Mountain Lion. Take that whole last paragraph about Snow Leopard and assume I meant Mountain Lion. So I did try your advice, but that did not work which prompted me to come here.

So I tried a fresh reinstall from OS X utilities, it's mountain lion still on this machine, but fine. It runs through its 30 minute install and then I get at the very end "An error occurred while preparing the install. Try again." I have tried like 3 times, no dice. I have looked it up and saw that it could have been related to a date/time thing, but checked the console and the date/time are correct. And I have tried it from both CMD-R and CMD-OPT-R.

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Answer 3

Kappy

Level 10

361,741 points

Jul 5, 2015 4:58 PM in response to kennfusion

Are you reinstalling over an existing installed system or are you doing a clean install by erasing then installing? You may have a defective installer download. What are you installing from: download, existing installer on the computer, USB flash drive installer?

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Answer 4

kennfusion Author

Level 1

15 points

Jul 5, 2015 5:05 PM in response to Kappy

I am trying to do a clean install. I started by erasing the hard drive. So I have a completely clean system with nothing on it except the existing installer on the computer, which is what I have tried to use. I also read that if I boot into the utilities with CMD-OPT-R it would force it into an over the internet install, which I tried (although I could not really tell if it was different than using the install from on the machine) but it had the exact same problem. "An error occurred while preparing the install. Try again."

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Answer 5

Kappy

Level 10

361,741 points

Jul 5, 2015 5:10 PM in response to kennfusion

I am not sure if you are doing what should be done, so if you would try my method. This is the Network Recovery you tried, but be sure you follow these instructions. Do not copy anything to the HDD either before or after doing the installation. You will need a clean, high-speed Internet connection. I suggest you only use Ethernet.

Install OS X Using Internet Recovery

Boot to the Internet Recovery HD:

Restart the computer and after the chime press and hold down the COMMAND-OPTION- R keys until a globe appears on the screen. Wait patiently - 15-20 minutes - until the Recovery main menu appears.

Partition and Format the hard drive:

Select Disk Utility from the main menu and click on the Continue button.
After DU loads select your newly installed hard drive (this is the entry with the mfgr.'s ID and size) from the left side list. Click on the Partition tab in the DU main window.
Under the Volume Scheme heading set the number of partitions from the drop down menu to one. Click on the Options button, set the partition scheme to GUID then click on the OK button. Set the format type to Mac OS Extended (Journaled.) Click on the Partition button and wait until the process has completed. Quit DU and return to the main menu.

Reinstall OS X: Select Reinstall OS X and click on the Install button. Be sure to select the correct drive to use if you have more than one.

Note: You will need an active Internet connection. I suggest using Ethernet if possible because it is three times faster than wireless.

This should restore the version of OS X originally pre-installed on the computer.

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Answer 6

kennfusion Author

Level 1

15 points

Jul 5, 2015 5:51 PM in response to Kappy

I tried to follow that exactly, but I must be doing something wrong, (which I already figured since I have been trying to resolve this all day now). As you ca see in the image below, I don't see anything that says Volume Scheme, and the options below the Partition Layout is grayed out. I have no idea what I am doing wrong here. 😐

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Answer 7

Kappy

Level 10

361,741 points

Jul 5, 2015 6:03 PM in response to kennfusion

I don't see what is wrong. You have a new volume named "I am freshly erased." The buttons are grayed out because there is no available action. Quit Disk Utility then select Install OS X from the main menu and click on the Continue button.

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Answer 8

kennfusion Author

Level 1

15 points

Jul 5, 2015 6:11 PM in response to Kappy

Well I do appreciate your trying to help. I have gone through this several times today already and as you can see, it looks like it is going to install, but then at the very end it will say "An error occurred while preparing the install. Try again." But, trying one last time today. Crossing my fingers.

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Answer 9

kennfusion Author

Level 1

15 points

Jul 5, 2015 6:20 PM in response to Kappy

Unfortunately, 5th time was not a charm. 😟 Any other thoughts?

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Answer 10

Kappy

Level 10

361,741 points

Jul 5, 2015 6:26 PM in response to kennfusion

I'd have to guess a download glitch of some kind or a bad hard drive.

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Answer 11

kennfusion Author

Level 1

15 points

Jul 5, 2015 6:33 PM in response to Kappy

Alright. Thanks for trying. I have been thinking it might be the hard drive failing all day, but was really hoping that was not it. Carrying a 27" iMac to the Apple store from South Brooklyn into Soho on the subway is never fun. Oh well.

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Answer 12

Jul 5, 2015 6:52 PM in response to kennfusion

Is this a fusion drive? If yes this might help.

The steps I took:

I booted from recovery mode (Hold 'Command' and 'R' while starting up)
From the menu screen ... On the top bar I selected 'Utilities > Terminal'.
This opened a terminal window.
Then I typed: diskutil CoreStorage list
And hit 'Return' ...
This showed the main storage drive details.
From there I found the UUID string ...
Which is basically the long number displayed under the storage drive name.
I selected and copied this ...
Then I typed: diskutil CoreStorage delete
Followed by the UUID string number ... And hit 'Return'.
The system then erased the main drive (it left the recovery dive intact though).
I then quit Terminal ... And went back into 'Disc Utilities'.
Only to find all of the drives displayed individually and in red ...
The 'Solid State Drive' and the 'Hard Disc Drive' were no longer displayed as one 'Fusion' unit.
However ... Upon clicking on one of the drives ...
The system recognised they were not unified ... And prompted me to fix this.
I asked the Disk Utilities to 'Fix' ... And the system returned to its normal state.
With the drives displayed as:

• Internal Drive • Macintosh HD

I was then able to install the OS X on the 'Macintosh HD' partition.
Note: To copy and paste while in terminal select the text then command C to copy and command V to paste.
Good luck. Tom

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Answer 13

kennfusion Author

Level 1

15 points

Jul 6, 2015 2:55 AM in response to EVISCERATOR

Wow, ok. That actually worked. Upgrading to Yosemite now and everything. Thanks! There is still an open question for me as to whether it is a failing hard drive, or the data just got corrupted. This re-install will fix the later. Only time will tell me if my HD needs to be replaced. But thanks again for taking the time out to post this, as it did allow me to install mountain lion. 🙂

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Answer 14

Jul 6, 2015 4:34 AM in response to kennfusion

Your welcome; I had a similar problem with my iMac and this fixed it and all is well with my hard drive. I think that your machine's hard drive is ok and that somehow the OS got corrupted. Happy computing: Tom

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Answer 15

Jul 6, 2015 4:40 AM in response to kennfusion

Oh, one more thing. Use migration assistant to restore your data from a back up.

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