MacOS – Issues creating Bootable USB for EL Capitan Public beta

bootable-diskmacosusb

I'm trying to follow tutorial over at: http://osxdaily.com/2015/06/11/make-bootable-os-x-el-capitan-beta-install-usb-drive/

to create bootable usb for El Capitan Public Beta, however after completion I get this error in console: 

Mount of outer dmg failed.

I tried running

hdiutil verify /Applications/Install\ OS\ X\ El\ Capitan\ Public\ Beta.app/Contents/Resources/createinstallmedia

And it returned:

hdiutil: verify: unable to recognize "/Applications/Install OS X El Capitan Public Beta.app/Contents/Resources/createinstallmedia" as a disk image. (image not recognized)
hdiutil: verify failed - image not recognized

I'm not sure why. I downloaded beta installer and it launched correctly. It sits in Applications folder.

Best Answer

I tried many things talked about here and on other top Google searches:

  • Redownloaded (three times)
  • Tried moving the .app to Desktop
  • Changed permissions of .app
  • Verified the .dmg with hdiutil
  • Used different Mac

Eventually got it to work by using a different USB flash drive. My original USB was a 16 GB Kingston, the second I tried that also didn't work was a 8 GB Lexar. The third and final one that did not get the "mount of outer dmg failed" error is a PNY 8 GB.

For reference I used the command:

sudo /Applications/Install\ OS\ X\ El\ Capitan\ Public\ Beta.app/Contents/Resources/createinstallmedia --volume /Volumes/Untitled --applicationpath /Applications/Install\ OS\ X\ El\ Capitan\ Public\ Beta.app --nointeraction

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