If you have previously downloaded Sierra, or if your Mac is compatible, you can try the official link.
Do not download random DMG files from third-party forums. They are often tampered with. Use Apple’s official links.
After installation is complete:
Install macOS Sierra:
macOS Sierra remains a robust operating system for older hardware. Whether you are downgrading for speed or compatibility, acquiring the DMG and using the createinstallmedia command is the most reliable way to get the system up and running.
*Note: macOS Sierra is no longer receiving security updates from Apple. Ensure you have a good antivirus and safe browsing habits if you use
Downloading and installing macOS Sierra (10.12) is straightforward if you use the official Apple-provided disk image. This version is available directly from Apple's support pages because it is no longer listed on the standard App Store search. 1. Download the macOS Sierra DMG To get the official file, follow these steps:
Visit the official download source: Go to the Apple Support page for downloading macOS.
Locate the link: Scroll down to the "Use a web browser for older versions" section and click the link for Sierra 10.12.
Download: Safari will download a file named InstallMacOSX.dmg to your Downloads folder. 2. Extract the Installer App
The DMG file contains a package that installs the "Install macOS Sierra" application into your Applications folder. It does not install the OS yet. Double-click InstallMacOSX.dmg to mount it. download macos sierra 1012 dmg file install
Open the mounted disk and double-click the InstallMacOSX.pkg file.
Follow the onscreen prompts. When finished, you will find a new app called Install macOS Sierra in your Applications folder. 3. Create a Bootable USB Installer
You need a USB flash drive with at least 8GB or 16GB of space.
To download and install macOS Sierra 10.12, you must use Apple's official legacy support links, which provide a disk image (.dmg) file. This process is multi-step because the .dmg contains a package (.pkg) that must be "installed" to generate the actual installation app. 1. Download macOS Sierra 10.12
Apple provides the official macOS Sierra 10.12.6 disk image directly through its support website. File Name: InstallOS.dmg
Requirements: It is recommended to use Safari to ensure the download works correctly.
Source: Only download from Apple Support to avoid security risks associated with third-party sites. 2. Extract the Installer App
Simply downloading the .dmg does not give you the installer. You must "install" the installer: Open the DMG: Double-click InstallOS.dmg to mount it.
Run the PKG: Inside the mounted image, double-click the InstallOS.pkg file.
Complete the Setup: Follow the on-screen prompts. This will not install the OS yet; instead, it places a file named "Install macOS Sierra.app" into your Applications folder. If you have previously downloaded Sierra, or if
3. Create a Bootable USB Installer (Optional but Recommended)
For a clean installation, create a bootable USB drive (minimum 16 GB required).
Format the Drive: Use Disk Utility to format your USB as Mac OS Extended (Journaled) with a GUID Partition Map. Name the volume MyVolume.
Terminal Command: Open Terminal and run the following command to move the installer files to the USB:
sudo /Applications/Install\ macOS\ Sierra.app/Contents/Resources/createinstallmedia --volume /Volumes/MyVolume --applicationpath /Applications/Install\ macOS\ Sierra.app Use code with caution. Copied to clipboard
Authenticate: Enter your administrator password when prompted and wait for "Copy complete" to appear. 4. Install macOS Sierra
Direct Install: If you are already on an older macOS version (like El Capitan), you can simply double-click the "Install macOS Sierra" app in your Applications folder and follow the prompts.
Boot from USB: Restart your Mac while holding the Option (Alt) key. Select the USB installer from the boot menu and follow the instructions to install.
To install macOS Sierra 10.12, you must first download the official disk image (.dmg) file from Apple, extract the installer application, and then run the installation either directly or via a bootable USB drive. Step 1: Verify System Compatibility
Before downloading, ensure your Mac supports macOS Sierra (10.12). The general requirements include at least 2GB of RAM and 8.8GB of available storage. Compatible Mac Models: MacBook: Late 2009 or newer MacBook Pro: Mid 2010 or newer MacBook Air: Late 2010 or newer Mac mini: Mid 2010 or newer iMac: Late 2009 or newer Mac Pro: Mid 2010 or newer Step 2: Download the macOS Sierra DMG File Direct Download : Apple sometimes provides direct download
Apple provides official links for older macOS versions through a web browser rather than the standard App Store search.
Visit the official Apple Support Download Page for older macOS versions.
Locate the Sierra 10.12 link to download the InstallOS.dmg file.
Ensure you use Safari if other browsers fail to initiate the download. Step 3: Extract the Installer App
The .dmg file is not the actual installer; it is a container for the installation package. Double-click InstallOS.dmg to mount the disk image.
Open the mounted image and double-click the InstallOS.pkg file.
Follow the prompts. This will not install the OS yet; instead, it extracts the "Install macOS Sierra" application into your Applications folder. Step 4: Install macOS Sierra
You can now choose between a direct upgrade or creating a bootable drive for a clean install. Option A: Direct Installation (Upgrade) Go to your Applications folder. Double-click Install macOS Sierra.
Click Continue and follow the on-screen instructions to complete the upgrade. Option B: Create a Bootable USB (Clean Install) How do I install MacOS Sierra DMG to Bootable USB?
| Error | Solution |
|-------|----------|
| "This copy of the Install macOS Sierra application is damaged" | Open Terminal and run: date 0101010116 (sets date back to 2016) then retry. |
| "macOS could not be installed on your computer" | Reset NVRAM (Cmd+Opt+P+R) and SMC. |
| "You need a firmware update" | Your Mac is too new (2015+) and never supported Sierra. |