Mac 101- Everything You Need To Know About FileVault Encryption.
You disk is undergoing full-disk encryption that was enabled automatically during setup because when asked you accepted the setup's default to encrypt the disk. Now, either you wait for it to finish, which could take hours to days, or you shutdown the computer then erase the disk and reinstall macOS.
To shutdown you need to press and hold down the Power button (also used for Touch ID) until the computer shuts down. Wait 30 seconds, then do the following:
Internet/Network Recovery of El Capitan or Later on a Clean Disk
If possible back up your files before proceeding.
- Restart the computer. Immediately, at or before the chime, hold down the (Command-Option-R) keys until a globe appears.
- The Utility Menu will appear in from 5-20 minutes. Be patient.
- Select Disk Utility and click on the Continue button.
- When Disk Utility loads select the target drive (out-dented entry w/type and size) from the side list.
- Click on the Erase button in Disk Utility's toolbar. A panel will drop down.
- Set the partition scheme to GUID.
- Set the Format type to APFS (SSDs, only if installing Mojave or Catalina ) or Mac OS Extended, (Journaled.)
- Click on the Apply button, then click on the Done button when it activates.
- Quit Disk Utility and return to the Utility Menu.
- Select Install OS X and click on the Continue button.
When the computer restarts to the Setup Assistant, watch carefully as you work through the screens. Watch for the one that will ask if you wish to accept the default setting for disk encryption. When it appears be sure to uncheck the option. Unless you are employed by an organization that requires data encryption on your computer, then you may not need to enable full-disk encryption unless you will store sensitive data on the disk.
