In the event that you need to unlock an unbootable FileVault-encrypted boot drive on macOS Mojave, it’s possible to do so using Disk Utility and the password to a FileVault-enabled account on the drive.
For more details, see below the jump.
To unlock an encrypted boot drive, please use the procedure shown below:
Note: For this example, I’m using Recovery HD‘s Disk Utility though you can also use Disk Utility from a regular boot drive.
1. Open Disk Utility.
2. Select the locked encrypted drive.
3. Click the Mount button.
Alternatively, you can select the Mount command under the File menu.
4. In the password blank which appears, enter the password to a FileVault-enabled account on the drive.
5. If the authentication is accepted, the drive should unlock and mount.
Note: You will not be able to decrypt from Disk Utility on macOS Mojave. If decryption is necessary, you will need to use the command line method documented at the link below:
One item of interest is that on macOS High Sierra, it is possible to unlock a FileVault-encrypted boot drive with Disk Utility using one of the following authentication credentials:
- The password to a FileVault-enabled account on the drive
- A personal recovery key
As of macOS Mojave 10.14.2, the ability to use a personal recovery key with Disk Utility to unlock an encrypted drive has apparently been removed.