To keep that file, you will want to move it out of the Applications folder so it won’t be deleted after an upgrade. Note: If you run the macOS Sierra installer to upgrade your Mac, the downloaded file will be deleted automatically after the upgrade is completed. It will save the installer as an “/Applications/Install macOS Sierra.app” file (about 4.97GB in size). Run the “App Store” application, search for “macOS Sierra”, and download it.

The macOS Sierra installer is available from the Mac App Store. The best advice for installing macOS Sierra is to try again and be very patient (if you expect an operation to complete in 5 minutes, then give it at least 50 minutes). Note: The macOS Sierra Disk Utility and installer appears to be more buggy and much slower than previous versions. Below are the steps I took to create the bootable USB flash drive and how I used it to install macOS Sierra. To perform a clean installation of macOS Sierra (basically, Mac OS X 10.12), I recommend using a bootable USB flash drive containing the macOS Sierra installer.