Unofficial archive. This is a read-only, community-run archive of the Apple Support Community. It is not affiliated with or endorsed by Apple Inc.
jools5858
User level: Level 1 (4 points)

How do I decrypt and access an APFS drive on a 2017 MacBook Air that won't boot?

I have a 2017 MacBook Air that won't boot. Whenever I enter the login password it gets halfway through the login progress bar and restarts the computer. I launched recovery and went to reinstall Monterey hoping to resolve the issue, but when I select the drive is asks for the password, which I enter, then it is giving me a message saying "you may not install to this volume because it is currently being decrypted". I left it like that overnight (twice), but it never actually does anything. I don't want to just wipe it, as there is data on it I need. I had a copy of High Sierra on an external drive which I then booted to, and in that OS the internal drive doesn't show in Finder. I can see it in Disk Utility, but it's greyed out. When I go to mount it, it asks for the admin password for the external drive OS, but then doesn't do anything. I'm assuming it's File Vault encrypted, but I have the password and everything, why won't it decrypt?



[Re-Titled by Moderator]

Original Title: Cannot access APFS drive

Posted on Nov 1, 2026 4:07 PM

8 replies

HWTech
User level: Level 9 (78,350 points)

Nov 2, 2026 11:41 AM in response to jools5858

Try booting into Safe Mode to see if that makes any difference.


Unfortunately if the drive is in the middle of encrypting or decrypting, then your options here are very limited since it may not be possible to run First Aid on it, nor use any type of data recovery software since the file system is in a state of flux.....partially encrypted and partially unencrypted.


What version of macOS is currently installed on the internal SSD of this MBAir?


If the current version of macOS on the internal SSD is macOS 10.15+, then accessing the data from High Sierra will be a bit tricky due to the drive layout changes with macOS 10.15+ which High Sierra doesn't fully understand. You will need to make sure the "Data" volume for the internal SSD is mounted. Unfortunately Apple has used multiple names for it over the years & various macOS versions, but it will at the very least have "Data" in its name.....could just be "Data" or it could be "Macintosh HD - Data", etc. If this internal "Data" volume is mounted, then you will need to access it at "/Volumes" where it will likely be "Data" or "Macintosh HD - Data", or whatever custom name you may have given it. Don't try to access your data through the traditional "Macintosh HD" volume (without the "Data" part in its name) as its User Folder will be empty. Only the actual "Data" volume will contain a "Users" folder with your macOS home user folder & data. Even if you have a later version of macOS boot drive, it can still be tricky accessing the actual "Data" volume....High Sierra is definitely capable of accessing it using the tips I mentioned.


If you try using Disk Utility First Aid, then first run First Aid on the physical drive, then on the hidden APFS Container. See the following Apple article for details on how to make the physical drive & hidden Container visible in Disk Utility.

How to repair a Mac storage device with Disk Utility - Apple Support

HWTech
User level: Level 9 (78,350 points)

Nov 5, 2026 6:54 PM in response to jools5858

jools5858 wrote:
The internal drive is running Monterey. The Data drive shows in Disk Utility, and has an option to mount, but it won't mount when selected. I ran First Aid on the physical drive, then the container, then attempted on the Data drive, but got an error on that one.

The First Aid errors on the "Data" volume are what is causing both the difficulty with mounting the volume as well as its decryption.


You can try using the Terminal command line to manually mount the "Data" volume read-only. I've never been successful at manually mounting a volume with First Aid errors.


If you wish to try....this is tricky to explain if you are not familiar with the command line. You will first need to acquire the device identifier for the "Data" volume by using Disk Utility (the device identifier can change each time you boot or connect a drive so it must be retrieve just prior to using the Terminal command).


diskutil  ap  unlockVolume  diskXsY  -nomount

diskutil  mount  readOnly  diskXsY


Replace "diskXsY" with the actual device identifier for the "Data" volume. If the device identifier is "disk3s6", then the commands would become:

diskutil  ap  unlockVolume  disk3s6  -nomount

diskutil  mount  readOnly  disk3s6


TheLittles
User level: Level 10 (211,627 points)

Nov 1, 2026 4:22 PM in response to jools5858

"How do I decrypt and access an APFS drive on a 2017 MacBook Air that won't boot?"

-------


About this Message:

"You may not install to this volume because it is currently being decrypted"

Wait it Out: Leave this plugged in (to avoid the Mac form falling asleep), and place it atop a laptop cooler. It is doing its thing: decrypting. It will take time --the larger the drive, the longer it will take.

TheLittles
User level: Level 10 (211,627 points)

Nov 1, 2026 10:10 PM in response to jools5858

"I left it 24hrs or more though. Would it take that long?"

-------


Yes. For a hard drive, it can take days, if not weeks. All the binary 1s and 0s ned to be placed how and where they should be --and that's what takes so long.


jools5858 Author
User level: Level 1 (4 points)

Nov 2, 2026 6:45 PM in response to HWTech

The internal drive is running Monterey. The Data drive shows in Disk Utility, and has an option to mount, but it won't mount when selected. I ran First Aid on the physical drive, then the container, then attempted on the Data drive, but got an error on that one.

HWTech
User level: Level 9 (78,350 points)

Nov 5, 2026 6:38 PM in response to jools5858

jools5858 wrote:
So this is day 4 and still not decrypted. I don't think there's any way it would take 4 days or more to decrypt 80GB of data. Of which probably 30GB is the OS... (The rest is unused on the drive).

Was the laptop still powered on during that time?


FYI, the OS portion of the drive no longer gets encrypted since macOS 10.15+ because it is now on a read-only volume (also signed & sealed as of macOS 11.x+). Only the "Data" volume containing user data is now encrypted (along with system configurable settings which are hidden on that "Data" volume).

jools5858 Author
User level: Level 1 (4 points)

Nov 1, 2026 5:21 PM in response to TheLittles

I left it 24hrs or more though. Would it take that long?

jools5858 Author
User level: Level 1 (4 points)

Nov 4, 2026 4:31 PM in response to jools5858

So this is day 4 and still not decrypted. I don't think there's any way it would take 4 days or more to decrypt 80GB of data. Of which probably 30GB is the OS... (The rest is unused on the drive).

Originally posted at discussions.apple.com/thread/256387165