Prepare - Things to do - Before upgrading OS X

Details

Before running an and OS X upgrade there are a few things to do first.

1. Be sure you have a current backup of your data (CrashPlan/Time Machine/OneDrive, etc).
2. Be sure there is at least 30GB of free space on the hard drive.
   • As a best practice, we always recommend keeping at least 15-20% free space on a drive.
3. Shut the machine down completely, then restart.
4. Go to Applications -> Utilities and open Disk Utility
5. In Disk Utility,
   • Make sure your internal drive “Macintosh HD” is selected on the left.
   • Click the First Aid tab at the top of the window.
   • “Run” First Aid on your drive.
6. Once First Aid has completed, if everything is OK and there are no issues that need to be repaired or addressed, then you can go forward with an OS upgrade from the App Store.
   • But If there are issues noted by First Aid, you will have to boot from the Recovery partition (Command+R at startup), then
     • Run Disk Utility,
     • Click First Aid Tab
     • Run First Aid on the drive so it can try to repair issues.
   • If repair is successful you can proceed with OS upgrade, but if not consider options (like a clean install) instead of upgrading.

Before you launch the OS upgrade,

1. Be sure all previous upgrades for the current OS have been installed.
2. Be sure to have the power adapter connected to the computer.
3. Disconnect  accessory devices like external keyboard, mouse, monitor, drives, etc.
4. Once again do a complete shut down and restart, and quit any applications you have set that launch on startup.

Be prepared to be patient, OS upgrades can take 40 minutes or more. Often they happen in segments too. So even if the display looks black like it isn’t doing anything, wait. You will ultimately see the login screen when the upgrade is done.