I need to solve this by tomorrow morning. how do I do that? On the IMac in question I cannot access any software that will allow me on to the internet to download Yosemite - I have Macbook Pro : Can I download the OS on to an external hard drive and use it to boot/install on the Imac? Where can I get an 'external' copy of Yosemite (I have looked but found nothing). Boot the computer you want to install El Capitan on with 'alt' held and select. Then, choose the disk you want to install the El Capitan installer on.

This USB will be used exclusively for downloading and saving Mac OS X El.

This basically comes down to your hardware is too. Select 'On an external drive' on the main MCPF window. In order to clean install OS X El Capitan, you must have a USB with 8GB free space. Simply put, if your Mac isnt old enough to run the latest El Capitan operating system then it wont install. I read online that this is a common problem when trying to install OS X El Capitan 'directly', and that I first need to install Yosemite. Make sure you have Install OS X El Capitan.app in your Application Folder 2. but it will not install!! I keep getting prompted to re-enter my account info, which is accepted, but when I click on 'continue', another page appears again asking me to log in. The problem is that when i do so (apple id etc all OK), i am prompted to install OS X El Capitan. The computer now boots up into the Utility Disk, prompting me to reinstall OS X. i thus did a full erase of all the data (only backing up the files I needed).

Hi, I am due to hand over my Imac (2012) tomorrow.

Install os x el capitan