Q: error creating yosemite boot disk

OS X Daily is not a respectable publication and I wouldn't trust anything it says. Apple's instructions are here:

Create a bootable installer for OS X Mavericks or Yosemite - Apple Support

Why not simply drag the "Install OS X Yosemite" icon to a properly formatted USB flash drive? It's a lot simpler; you just won't be able to boot from it directly.

You can make a bootable USB stick to install using this free program. It does all the work for you.

Bootable USB Flash Drive – Diskmaker X

I had the same problem. I found out it was because my HDD had the same name as the USB. After formatting the USB with a new name it worked perfectly fine.

The error is because of "access issue". Your volume you want to make bootable is in use with some other application(may be in terminal- if you are in that directory). just move to home directory and try again.

"Worked for me"

Life saver! Thank you!

I had the same error, and found that it was because there was a phantom mounted volume called "Untitled."  There are several solutions to this; manually force unmount the volume, reboot, or simply rename the USB flash drive.  I chose the latter, renamed it "Untitled111" and used this modified command:

sudo /Applications/Install\ OS\ X\ Yosemite.app/Contents/Resources/createinstallmedia --volume /Volumes/Untitled111 --applicationpath /Applications/Install\ OS\ X\ Yosemite.app --nointeraction

In my case I had an app (Final Cut Pro) which was using the drive for some unknown reason. I found this out when I tried to eject the drive, it wouldn't eject. After quitting Final Cut Pro the error went away.

Make sure you don't have the USB open in Finder and also make sure you're not in the USB in iTerm!

Thanks. This helped me. I could not even unmount the drive first. Some stuff kept a link open to the drive.

FInally I unmounted and remounted then the erase went trough ok. This is with El Capitan.

Thanks man after all the reading I had done this was the one that took. Plus I took the space out from between the /_Untitled111. The Underline was a space and I removed that as well.

Thanks Worked Great!!

Apple has a page dedicated to this:-

Create a bootable installer for OS X - Apple Support

I wanted a boot disk for Yosemite 10.10.5 which I currently have, before I upgrade to El Capitan, just in case I don't like the upgrade. I used the instructions in "How to install OS X on an external drive connected to your Mac". The directions are clear and don't involve command line use.

I purchased a 32 GB  !!! USB 3 stick and carefully erased and formatted it as per instructions. I originally had created two partitions with 10.2 GB allocated for the OS X download, but it said it wanted about 10.5 so I made the USB stick one partition and made all 30 GB available so it would have PLENTY of room.  Numerous tries at download hung up with about 15 min remaining.

Solution: I uninstalled Malware Bites anti-malware program.  First try after that went flawlessly

Side note: my iMac was not purchased from Apple, and came pre-loaded with Yosemite. So I could not go to the App store and get to a record of my "purchase" of Yosemite. And by now they only offer El Capitan to download. The above procedure allows for authentication using your computer's serial number sent to Apple during the Install from OS X recovery.

Hope this helps someone.