
Just grab yourself a cup of coffee and return after at least half an hour to check on the progress. We would highly recommend not touching or using your Mac at all during the entire process. The process can take quite a while so don't be alarmed. Provided you followed the steps correctly, your Mac will now start creating the bootable macOS Sierra Developer Preview USB drive. Sudo /Applications/Install\ 10.12\ Developer\ Preview.app/Contents/Resources/createinstallmedia -volume /Volumes/Untitled -applicationpath /Applications/Install\ 10.12\ Developer\ Preview.app -nointeraction &say Doneĭouble check and make sure the command line perfectly matches the one above and hit the 'Return' key on the keyboard.Ĩ. Now type in the following command exactly as shown: Assuming macOS Sierra Developer Preview is done downloading, launch Terminal on your Mac.ħ.

We would recommend leaving the name of the drive to 'Untitled' as well.Ħ. Leave everything else untouched and click on the 'Erase' button. Select your USB drive from the left hand side corner of Disk Utility.ĥ. Launch Disk Utility from Spotlight or Launchpad.Ĥ. First and foremost download the macOS Sierra Developer Preview image from the Mac App Store.

