OS X Lion 10.7.5 or later is required to upgrade directly Part 2: How to Download macOS Sierra 10.12 DMG File
If you are trying to download Sierra on a Mac that is too new (macOS blocks downloads for incompatible hardware), you can use the or a patcher tool created by the community (like DosDude1's patchers). These tools bypass the hardware check to download the installer directly from Apple's servers.
Unlike modern macOS installers, working with Sierra comes with specific requirements and known issues. Prepare these before you begin:
Before you invest any time, it's crucial to ensure your Mac is actually compatible with macOS Sierra. It's also worth noting that macOS Sierra was the last version to support the HFS+ file system before Apple transitioned to APFS with High Sierra. download macos sierra 1012 dmg file install
⚠️ Downloading macOS from unverified sources may violate Apple’s software license agreement and expose your system to security risks.
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.
Follow the prompts. This will place a new app called "Install macOS Sierra" in your Applications folder. 3. Install macOS Sierra OS X Lion 10
Use the arrow keys to select and press Enter .
Post‑install
macOS Sierra (version 10.12) is a significant operating system update for Mac, introducing Siri to the desktop, the Apple File System (APFS), and features like Universal Clipboard. While Apple has since released newer versions (Catalina, Big Sur, Monterey, Ventura, Sonoma), there are still legitimate reasons to need the Sierra installer—specifically for downgrading hardware, performing a clean install on older Macs, or running the OS in a virtual machine. Prepare these before you begin: Before you invest
From the macOS Utilities window, select and click Continue .
Unmount (eject) the temporary virtual InstallOS disk image when the wizard finishes. Step 3: Install macOS Sierra (Standard Upgrade Method)
Press to confirm you authorize the volume to be erased, then wait for the terminal to print a line indicating success ( Update complete. Done. ). Boot From the USB Drive Shut down the target Mac completely.