Basic Steps for Upgrading OS X
- Repair the Hard Disk Drive and permissions.
- Update all third-party applications for compatibility, if needed - See App Compatibility Table - RoaringApps.
- Backup your data. Or use the Restore option of Disk Utility to clone your system to a backup drive.
- Verify the backup is where it should be. If you cloned verify the clone will boot the computer.
- Download the upgrade from the App Store.
- Before installing make a copy of the installer for safe keeping.
- install the upgrade.
You can upgrade only as far as High Sierra - How to upgrade to macOS High Sierra.
Bootable USB Installer for High Sierra
First, review this introductory article: Create a bootable installer for macOS. Second, read this How To outline for creating a bootable macOS installer. Simply use the Terminal command by copying and pasting the command line for the version of macOS below. You will need an 8GB or larger USB flash drive that has been partitioned and formatted for use with OS X as well as an installer for the macOS version that you have previously downloaded from the App Store.
Drive Partition and Format
- Open Disk Utility in the Utilities' folder.
- After Disk Utility loads select the drive (out-dented entry with the mfg.'s ID and size) from the side list.
- Click on the Erase button in the Disk Utility toolbar. Name the drive, "MyVolume". <---- IMPORTANT!
- In the drop down panel set the partition scheme to GUID. Set the Format type to Mac OS Extended (Journaled.)
- Click on the Apply button and wait for the Done button to activate. When it does click on it.
- Quit Disk Utility.
Create Installer
Open the Terminal in the Utilities' folder. Copy the command line (begins with "sudo"). Paste that entire command line from below at the Terminal's prompt:
Command for macOS High Sierra:
sudo /Applications/Install\ macOS\ High\ Sierra.app/Contents/Resources/createinstallmedia --volume /Volumes/MyVolume --applicationpath /Applications/Install\ macOS\ High\ Sierra.app
Press RETURN. You will be asked for your admin password. It will not echo to the Terminal window. Then press RETURN again. Wait for the return of the Terminal prompt signifying the process has completed. It takes quite some time to finish. Be patient.
The bootable installer can be used to install the selected version of macOS. Shut the computer down. Insert your flash drive into a USB port. Start the computer like so:
Boot Using OPTION key
- Restart the computer.
- Immediately after the chime press and hold down the "OPTION" key.
- Release the key when the Boot Manager screen appears.
- Select the disk icon for the USB flash drive.
- Click on the arrow button under the disk icon.
