FileVault 2 offers a great service: it encrypts the entire storage of your Mac. However, many people have experienced a problem. It doesn’t finish (for the record, this happened to me on 10.10.5. Some said the issue was resolved with 10.10.3). We see messages like:
Encrypting… Estimating time remaining
Unfortunately, this causes problems when upgrading OS X or trying to create a Boot Camp partition. Since FileVault shows as enabled and the drive shows as encrypted, I decided to decrypt the drive. This is done by:
- Booting into Recovery HD (restart the computer and hold Cmd+R until the Apple logo and progress bar appear).
- Open Disk Utility.
- Select the encrypted drive (it should be grayed out in the sidebar).
- Go to File > Unlock Macintosh HD, and enter password
- Go to File > Turn Off Encryption, and enter password.
- Reboot to OS X.
Ah, good. In a fairly short period of time, I should have my drive back. Except … decryption has the same problem! Interestingly, decryption becomes unpaused during disk verification (Open Disk Utility, select both “Macintosh HD” in the sidebar, and click Verify Disk). This lasts only a few minutes, however. I ended up using Verify Disk a number of times until decryption finished.
Once I installed El Capitan, I tried encryption again and encountered the same issue. So I continually ran First Aid until encryption finished. If you want a Boot Camp partition, however, you’ll probably need to wipe the drive and start fresh.
UPDATE 11/11/2015: Try the solution mentioned on this post.