To ensure compatibility with the macOS bootloader, the USB drive must be partitioned using the GUID Partition Map scheme and formatted with the Mac OS Extended (Journaled) file system. Connect your USB flash drive to your Mac.
"This copy of the Install OS X application cannot be verified" create mac os x bootable usb installer from dmg
Whether you are trying to revive an older Mac, upgrading multiple machines, or keeping a recovery tool handy, knowing how to is an essential technical skill. To ensure compatibility with the macOS bootloader, the
Apple includes a built-in command-line tool specifically designed to create bootable drives safely. Open (found in Applications > Utilities). If your DMG contains a
The createinstallmedia command (Apple’s official tool) requires the .app bundle, not a raw DMG. If your DMG contains a .pkg installer, you must run the package first to extract the .app to your Applications folder.
Many official Apple DMG downloads mount to reveal a standard installation application. If yours does, follow these steps using the native createinstallmedia tool.
sync sudo diskutil eject /dev/diskX