One of my external hard drives used for Time Machine backups has an encrypted HFS+ volume. While in the process of trying to re-associate the backup with my system, I accidentally told it to start decrypting the drive.

I don't want it to be decrypted! However I can't find any way of telling my system to stop! After searching around, I've found that you can use diskutil to stop a drive that's in the process of being converted to encrypted, but found no mention of any way to do halt a decryption conversion.

Help! What can I do? It's going to take forever to decrypt this massive drive, and I don't want it to even do that!

edit: This question is different from this one in that I am not using FileVault to encrypt this drive. It is an external drive with no macOS system on it used for Time Machine backups -- FileVault isn't involved.


1 Answer 1


Even though it is an external drive, the encryption system being used is still FileVault.

There's currently no method to cancel a decryption of the drive. You'll have to wait until the drive is fully decrypted, and then re-encrypt it.

  • That's quite unfortunate. I think I'm just going to blow away the drive and start fresh. It will take somewhere between 1.5 and 2 weeks for it to fully decrypt and re-encrypt the damned thing, and so far I've been wholly unable to get my system to inherit the Time Machine backup on there anyway.
    – Bri Bri
    Commented Jul 15, 2019 at 18:50
  • Probably faster yes. However note that sometimes the remaining time indication goes down/up a lot. You might want to leave it going for an hour or two and see how fast it really is.
    – jksoegaard
    Commented Jul 15, 2019 at 18:55

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