When prompted to confirm the erasure of the drive, type Y and press .
If you want to create a bootable installer for macOS Sierra 10.12, you'll need:
After successfully booting into Mac OS Sierra 10.12, do the following immediately:
Before downloading, ensure your hardware is compatible. Sierra generally supports: : Late 2009 or newer. MacBook Air / Pro / Mini / Pro : 2010 or newer.
Wait for the download to complete. The final file will save natively as InstallMacOSX.dmg . Step 2: Extract the Mac OS Sierra Installer Package
If you are using VMware or VirtualBox on Windows/Linux, you need an .iso file rather than a .dmg . You can convert the official DMG to ISO using Terminal, or find trusted community-provided ISO files that are pre-packed for virtualization.
As of 2026, Sierra is considered obsolete by Apple. It receives no security updates, and many modern apps no longer support it.
This is a very common problem and is almost always caused by downloading a combo update instead of the full installer .
Always verify your DMG via checksums, set the system date correctly if the certificate fails, and consider creating a bootable USB for future use. Preserve that DMG on an external drive or cloud storage; as time passes, clean copies of macOS Sierra become more valuable for retro-computing.
user wants a long article about downloading macOS Sierra 10.12 DMG. I need to gather comprehensive information. I'll follow the search plan as outlined. The first round involves official sources, third-party sites, compatibility, installation, and troubleshooting. I'll search for the Apple support page, a general guide, third-party download sites, a torrent/Pirate Bay option, compatibility info, installation instructions, and common issues. I'll also search for upgrade vs. clean install differences. I'll use the specified search terms. search results for the official Apple download and general guide pages have provided some links. I should open the most relevant ones to gather detailed information. The results for third-party sites, torrents, compatibility, installation, and troubleshooting also need to be opened. I'll open the Apple discussions, the iboysoft article, the Dortania guide, the GitHub page, the Apple support compatibility page, the Apple support bootable installer guide, and the iboysoft troubleshooting article. search results provide a good foundation. I have Apple discussion links with download instructions, an iboysoft article with DMG links and methods, a Dortania guide for legacy macOS, a GitHub page with direct links, Apple support pages for compatibility and bootable installer creation, and troubleshooting articles. I also have results for third-party download sites, torrents, and installation errors. Now I need to search for additional information on upgrade vs. clean install, creating a bootable USB installer, and installation troubleshooting. I'll use the specified search terms. have gathered a substantial amount of information covering official sources, third-party options, compatibility, installation, and troubleshooting. Now I need to structure the article. The outline includes an introduction, official DMG download methods, creating a bootable USB installer, system requirements, installation options, troubleshooting common errors, and a conclusion. I will cite the relevant sources throughout. Now I will proceed to write the article.OS Sierra (version 10.12) was a landmark release for Apple’s desktop operating system, representing the shift from the traditional "OS X" naming scheme to "macOS" to align with the company’s other platforms. It introduced beloved features such as Siri on the Mac, the Universal Clipboard, and Apple Pay on the web. While this system is several years old, many users still seek the full installer—the DMG file—to restore legacy hardware, maintain compatibility with older 32-bit software, or create virtual machines for development.
If your Mac is older than these models, it is not officially supported. While there are community-made patches to install newer macOS versions on older hardware, these can be complex and may result in stability issues (see the "Installing on an Unsupported Mac" section below).
If you're looking for alternative options to Mac OS Sierra 10.12: