Before you allow your Macbook or Macbook Air to update the operating system ….. make sure you have enough free disk space or you will turn it into a brick Many MacBook or MacBook Air users run them at 95% disk capacity, as they have very small SSD’s that fill up quickly. Check your capacity by clicking on the apple symbol in top left of screen “About this Mac” > “Storage” This example shows lots of spare capacity This example shows a lot less storage available. Click on “Manage” to try and free up some space or move photos, documents or data into iCloud. The biggest danger of “low-disk-space” happens when installing updates. The Mac cannot restart and perform the update which results in the “black-screen-of-death” where the cursor is alive but nobody else is home. If your lucky, restarting the Mac my get it back again. Make sure you empty the trash and free up some space ASAP. Else you may have to take it to your nearest Mac repairer. Click on About This Mac -> Software Update …now try “Update All” …. if your low on disk space you will get this warning. Free up some disk space and try again. :jk: