Apple’s FileVault disk encryption option in OS X is a security feature that is highly recommended, especially for portable systems that can be easily stolen. The feature is easy to set up in the Security system preferences, after which the system should take up to a few hours to encrypt the drive, depending on the size and type of drive being used. This should be relatively straightforward; however, in some cases the encryption may get stuck and show a progress bar that will not advance, even after days of waiting.
Generally if FileVault takes a few hours longer than expected to encrypt a drive, then it is recommended to simply wait it out, and be sure your Mac is connected to a reliable power source. However, even when connected and seemingly working properly, FileVault may be stalled.
This problem likely is happening because of errors in your hard drive’s partitioning and formatting, so to fix this problem, you will need to use Disk Utility in Recovery Mode:
- Reboot your Mac and hold Command-R at the startup sound to get to Recovery Mode.
- Open Disk Utility in the OS X Tools panel.
- Select your boot drive in the sidebar.
- Click the Unlock button, and then supply your FileVault password to unlock the drive.
- Hold the Command key and click the unlocked volume and the drive device in the sidebar to select them both.
- Go to the First Aid tab and click the “Repair Disk” button.
After doing this, you might as well run a permissions repair routine by selecting your boot volume and clicking the Repair Disk Permissions button. Then reboot your Mac, and log in as you normally would, and then check the progress of FileVault’s encryption. In most cases, the stall should pick up immediately and be done within a few minutes.