Can't update OS from 10.7.3 to Mavericks I have created a Mavericks OS bootable SD card that I am trying to get onto my Macbook pro 2011 model. 

Every time I try to boot from that card using 'Option' or by selecting to use it as t the startup disk. It just brings me back to the same old Lion 10.7 installer. 

On top of that I can't get that to install either because when I try to install it I get the error message 'This item is temporarily unavailable, try again later'

What do I do?
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Have you tried simply copying or downloading the entire Install OS X Mavericks.app to the drive you need to update &amp; running it from there? That's the prime update method.