Stopping encryption on a MacOS ver.10.12 Time Machine

Question

I recently ran into a problem encrypting my external drive 1 TB My Passport for Mac as a Time Machine disk. Its been locked at 97% completion for at least a week and can't seem to manage a TM backup. I'd like to keep previous backups and read a previous post suggesting using this script in Terminal:

diskutil cs revert /Volumes/title_drive -passphrase

I enter /Volumes/My Passport for Mac -Keychain password but terminal keeps returning this prompt:

Convert a CoreStorage logical volume back to its native type. If you are attempting to revert a disk on which conversion was started but which could not be unmounted, you must eject the disk or reboot first. The file system must be mounted and resizable (i.e. Journaled HFS+). Ownership of the affected disk and a passphrase (if encrypted) is required.

Not sure what I did wrong. I ejected the disk. The disk appears to be Journaled and mounted from this screenshot:

Running "First Aid" does not return anything wrong with the disk. I expect I have ownership for the disk as I'm the only user. For reference a print-out when I run diskutil cs list:

> +-- Logical Volume Group 44B2E0C9-D1E6-400A-9EF5-996691A05F07
>     =========================================================
>     Name:         My Passport for Mac
>     Status:       Online
>     Size:         999826612224 B (999.8 GB)
>     Free Space:   0 B (0 B)
>     |
>     +-< Physical Volume B57FA8EB-6A1B-4537-B251-FFA027AC023F
>     |   ----------------------------------------------------
>     |   Index:    0
>     |   Disk:     disk2s2
>     |   Status:   Online
>     |   Size:     999826612224 B (999.8 GB)
>     |
>     +-> Logical Volume Family 87A99FC9-1BB7-47FC-B6ED-DFDEEF68FB87
>         ----------------------------------------------------------
>         Encryption Type:         AES-XTS
>         Encryption Status:       Unlocked
>         Conversion Status:       Converting (forward)
>         High Level Queries:      Not Fully Secure
>         |                        Passphrase Required
>         |                        Accepts New Users
>         |                        Has Visible Users
>         |                        Has Volume Key
>         |
>         +-> Logical Volume B2A532CB-0C9D-4474-992F-0591DD2F90DC
>             ---------------------------------------------------
>             Disk:                  disk3
>             Status:                Online
>             Size (Total):          999469088768 B (999.5 GB)
>             Conversion Progress:   97%
>             Revertible:            Yes (unlock and decryption required)
>             LV Name:               My Passport for Mac
>             Volume Name:           My Passport for Mac
>             Content Hint:          Apple_HFS

Does anyone have any idea what's wrong?

Answer 1

You'll need to "escape" the spaces in your drive's name with backspaces, like this:

diskutil cs revert /Volumes/My\ Passport\ for\ Mac -passphrase

Use the flag "-passphrase" as written (you'll be prompted when to enter your actual passphrase).