Cannot Install OS X10.6

[toria]

I'm wanting to upgrade an iMac from OS X 10.5.8 to Mountain Lion, but appear to need to install Snow Leopard, then Lion, then Mountain Lion.

When I put the snow Leopard Disk in the iMac and boot from the install disk, it tells me I "Cannot install OS X on this computer." I've tried several times and get the same message. It goes through a few seconds of "preparing the installation" then comes back with "Cannot install OS X on this computer."

I have checked the technical requirements, and my computer meets them.

I am using a retail install disk.

I have repaired disk permissions using Disk Utility.

I have nothing hooked up to the computer other than the keyboard and mouse.

Trying to install on a 21 inch iMac with:

2.4 GHz Core 2 Duo
4 GB RAM
213 GB free disk space
OS X 10.5.8 (current OS)

Using Retail Snow Leopard 10.6.3 disk that I purchased from Apple.

Can anyone help with this?

Thanks in advance for your help.

Best,

Victoria

 

[blevins321]

Don't know why you're having snow leopard issues, but just FYI you can go straight from SL to ML without having to install Lion. Still only $20

 

[toria]

Thanks, blevins321.

In order to go from Snow Leopard to Mountain Lion, I need to get Snow Leopard on the iMac.

I am baffled as to why I cannot install it. There is no reason code given.

 

[wrldwzrd89]

I suspect file system damage that Disk Utility cannot repair as the reason the installer's aborting. This is easy enough to verify - run Disk Utility and choose Verify Disk.

 

[toria]

Thank you wrldwzrd89. I will do that. If there is corruption, what should I do?

 

[wrldwzrd89]

Unfortunately, fixing this sort of problem always requires a reformat. Fortunately, if you have a bootable clone and/or a Time Machine backup, recovering your data after the reformat is very easy. Make sure you update your backup first! For a bootable clone, boot from the clone and clone the clone back to the original, using your disk cloning software. For a Time Machine backup, you'll need to boot from an alternative disk in order to perform both the reformat and the restore. Since you're experiencing failures with the Snow Leopard disk you have, I don't recommend this method. Assuming you follow my advice and make a bootable clone, make sure the drive you use is either as big or bigger than the amount of data that needs to be copied. I've had the most success with FireWire drives, but Thunderbolt and USB ought to work too. If you need help selecting a disk cloning program, the ones I've used before and can recommend are Carbon Copy Cloner and SuperDuper - neither one is free, though.

 

[toria]

Thanks for your info!

This iMac has never been attached to an external hard drive, so no Time Machine backup. The computer belonged to my mom, who passed away. I don't care about restoring old files.

I copied all of the files to DVD before attempting to upgrade os x.

The only external HD I have is connected to my 27" iMac and is the Time Machine backup disk.

So, I don't have a clone or another disk to boot from. I suppose I could put the computer into Target Disk mode and connect it to my 27"iMac.

If I do that, could I reformat the drive and install Snow Leopard from the disk if I put the disk in my 27" iMac? Is that essentially like installing the OS onto an external HD, with the external HD being the 21" iMac in Target Disk mode?

UPDATE: I did a couple of things:

1. I put the 21" iMac into Target disk Mode and use the Disk Utility on my big iMac to verify the disk in the one I am trying to upgrade. Disk Utility said it was OK.

2. I used Rember to check the RAM in the recalcitrant computer and it all checked out OK.

I will attempt to install from my other iMac....

 

[wrldwzrd89]

Thanks for your info!

This iMac has never been attached to an external hard drive, so no Time Machine backup. The computer belonged to my mom, who passed away. I don't care about restoring old files.

I copied all of the files to DVD before attempting to upgrade os x.

The only external HD I have is connected to my 27" iMac and is the Time Machine backup disk.

So, I don't have a clone or another disk to boot from. I suppose I could put the computer into Target Disk mode and connect it to my 27"iMac.

If I do that, could I reformat the drive and install Snow Leopard from the disk if I put the disk in my 27" iMac? Is that essentially like installing the OS onto an external HD, with the external HD being the 21" iMac in Target Disk mode?

UPDATE: I did a couple of things:

1. I put the 21" iMac into Target disk Mode and use the Disk Utility on my big iMac to verify the disk in the one I am trying to upgrade. Disk Utility said it was OK.

2. I used Rember to check the RAM in the recalcitrant computer and it all checked out OK.

I will attempt to install from my other iMac....

Yes! Target Disk Mode works just as well for what you need to do.