So this was very weird for me. I was using my 32GB Sony Flash Drive (APFS, Encrypted), when all of sudden it got unmounted. When I mounted it back it did not ask for a password. The drive was listed simply as "APFS" by Disk Utility and most of the files are inaccessible except a random few. I do not know what happened.

The Disk Utility repair option gives the following output:

error: (oid 0x58c) apfs_root: btn: invalid o_cksum
fsroot tree is invalid.
The volume /dev/rdisk4s1 could not be verified completely.
File system check exit code is 0.
Restoring the original state found as mounted.
Operation successful.

Can anyone please help me with this?

I dont have a backup for many of the important files on the drive.

1 Answer 1


Sounds like the volume or media itself became corrupted. Corruption of portable media is common, especially if you are moving it around, mounting and un-mounting, in and out of your bag, hot and cold, etc.

If you really need the files, I'd recommend a reputable file recovery utility before doing anything else to the volume, and in the future, don't rely on portable media for critical files.

  • Thanks for the reply, Pixelwiz. I did try some file recovery apps, but they simply show the files as they are (unable to open). Since the drive was encrypted and suddenly lost its encryption, I think most of the files are still in the encrypted state hence not accessible. Is there a way to somehow force-change the file system of the drive from APFS to APFS(Encrypted)? Using some disk editor or something? I tried using iBored but couldn't figure much out. Dec 30, 2022 at 9:34
  • Recovering a damaged encrypted drive is virtually impossible; not even a data recovery company may be able to do this. You could try one, but really I'd consider the data lost & in future never entrust any single copy of any data to something so flimsy. "Any data in fewer than three distinct locations ought to be considered temporary."
    – Tetsujin
    Dec 30, 2022 at 12:43
  • Thanks for the input, Tetsujin. You have a point indeed. However, I think that the files are not corrupted but simply in an encrypted state, since a few files are still accessible. Since the file system of the APFS Encrypted now shows up as only APFS, I was wondering if i can somehow edit the file system of the drive so that it gets mounted as APFS Encrypted? Is that possible? Dec 30, 2022 at 16:43
  • 'Encrypted state' is your issue. You don't know where any of the data is, or where the encryption keys are - or even what they should look like if you ever found them. It's not like a spinny rust HD where you could plod through the sectors sequentially to see what you might scavenge. There is no concept of sequential on a solid state drive. Your only hope is a data recovery company & that hope is slim. Don't even try to make any changes yourself. Every single time you touch the drive you reduce your chances.
    – Tetsujin
    Dec 30, 2022 at 17:01
  • Oh, okay. Thanks Tetsujin Dec 30, 2022 at 18:54

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .