: Inside the mounted image, double-click the .pkg file. This is not the OS installation yet; it simply installs the "Install macOS Sierra" app into your Applications folder.
Below is a detailed, step-by-step guide to help you find and install this classic operating system safely, including how to fix the most common errors.
This report provides the necessary steps to download and install macOS Sierra (version 10.12) using a disk image (.dmg) file. While macOS Sierra is no longer receiving security updates , it remains available for users with older, compatible hardware.
Once the USB is ready:
Minimum 2GB (4GB recommended for better performance). Storage: At least 8.8GB of available space. Compatible Models: iMac: Late 2009 or newer. MacBook: Late 2009 or newer. MacBook Pro: Mid 2010 or newer. MacBook Air: Late 2010 or newer. Mac mini / Mac Pro: Mid 2010 or newer. 1. Official Download of the .dmg File
What is the of the Mac you are installing Sierra on? Are you downloading this file using a Mac or a Windows PC ? Share public link
Without these updates, Sierra will have the "Hole in the Boot" security vulnerability (CVE-2017-13890). download macos sierra 1012 dmg file install
Download macOS Sierra 10.12 DMG File: Complete Install Guide (2026)
Select your main computer hard drive, click (this will delete everything on the computer). Close Disk Utility and select Install macOS .
A significant problem exists with the macOS Sierra installer. There are widespread reports in Apple support communities that Apple's createinstallmedia tool is "broken" for this specific version of macOS, causing the creation of a bootable USB to fail. If you encounter the error /Volumes/MyVolume is not a valid mount point or similar issues, it is a known flaw in the installer. : Inside the mounted image, double-click the
Follow the sequential onscreen prompts. This script does install the operating system onto your Mac yet; instead, it extracts and builds the standalone Install macOS Sierra.app bundle and drops it directly into your native /Applications folder.
Inside the mounted disk image, double-click the .pkg file (often named InstallOS.pkg ).