# The following disk images couldn't be opened



## jltech (Feb 16, 2013)

Hi

I just bought Mountain Lion from the Mac App Store. I need to make a backup USB. But when I try to open InstallESD.dmg, it says "The following disc images couldnt be opened
Install ESD.dmg        Not recognized.

Could anyone help me? Any help would be appreciated!

Thanks


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## jltech (Feb 16, 2013)

I'm sure someone is out there to help me


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## Satcomer (Feb 16, 2013)

What Mac are you running?


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## DeltaMac (Feb 16, 2013)

Why do you need to open the InstallESD.dmg?

Just drag that file into your Disk Utility, and you can use the Restore tab to copy the image to a partition. 6GB should be great for the Mountain Lion installer.
You could also try using one of the apps that make the process easy. Lion Diskmaker works very nicely. I have several 8 GB flash drives, and have a couple dedicated for OS X installers. Lion Diskmaker (LDM) uses those, and erases them properly for best use with the Mountain Lion install. You can get that here: http://www.macupdate.com/app/mac/39701/lion-diskmaker
LDM will use a dedicated partition on a hard drive, or a USB flash key, or will also burn a DVD, whichever is what you want to do.
I suggest that burning a DVD is not worth your effort. Lion, and Mountain Lion installers are not optimized for booting from DVDs, and are really slow.
I think the best choice is an 8 GB flash key. My suggestion is to use a new flash drive just for the installer. You can find those everywhere for less than $10, and I have seen some for less than $6 ...

If that utility also doesn't like your Mountain Lion download - try restarting your Mac into Safe Boot mode (restart holding the Shift key), and try the same copy again.
If you still get the same error - then delete that download - it's likely just corrupted - and download again. You've already purchased the Mountain Lion install, so Apple doesn't charge you again.


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## jltech (Feb 17, 2013)

Satcomer said:


> What Mac are you running?



Mac OS X Mountain Lion


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## jltech (Feb 17, 2013)

DeltaMac said:


> Why do you need to open the InstallESD.dmg?
> 
> Just drag that file into your Disk Utility, and you can use the Restore tab to copy the image to a partition. 6GB should be great for the Mountain Lion installer.
> You could also try using one of the apps that make the process easy. Lion Diskmaker works very nicely. I have several 8 GB flash drives, and have a couple dedicated for OS X installers. Lion Diskmaker (LDM) uses those, and erases them properly for best use with the Mountain Lion install. You can get that here: http://www.macupdate.com/app/mac/39701/lion-diskmaker
> ...



Thanks for your help. I will try it later.

I need it to make a USB backup for my OS, but I need the specific ISO because I would like to boot from CDs. (I have no USB in house)


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## DeltaMac (Feb 18, 2013)

You said that you want to make a USB backup, but then you say that you don't have USB.

Your Mac has USB ports.
Are you saying that your USB ports are not working at all?

I also said that you can easily do this (make a backup) to a USB flash drive - which is what you can use for booting to the installer, on the flash drive. You need an 8 GB flash drive, which is easy to find, and low cost (less than $10)
AND - the flash drive will be much more reliable than booting to a DVD - faster, too!

Download the Lion Diskmaker that I mentioned. It's very easy to use, and works perfectly.


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