I had an HFS+ partition on an external drive that was encrypted first. I later removed the encryption and accessed it several times on a student library Mac.
Unfortunately, this drive wasn’t properly ejected due to the dodgy USB port on the Mac, and since then, the HFS+ partitions no longer show up in Disk Utility.
I left it for several months and connected it to another Mac. I noticed that both of my HFS+ partitions are now core storages when running diskutil list in Terminal.
They don’t seem to have a file system and don’t mount. I tried mounting one with mount -t hfs /dev/disk4s6 /Volumes/j3, and it was successful. The files and folders show up; however, many of them cannot be opened.
Running First Aid ended with the error “Error: -69716: Storage system verify or repair failed. Underlying error: 1: Operation not permitted.”
How can I recover those files? P.S. I’m running macOS High Sierra.
It sounds like your partition map is suffering from a “leftover” CoreStorage wrapper. When you encrypt a drive on macOS, it converts the partition into a Logical Volume Group (CoreStorage). Even though you “removed” the encryption, the drive is still behaving as if it’s managed by that logical layer, which is now corrupted due to the improper ejection.
Since you were able to manually mount the drive and see files, the data is likely still there, but the file system catalog is out of sync.
Since you successfully mounted the drive once via Terminal, your best bet is to bypass the Finder and use a robust copy command like rsync. This ignores minor file system errors that might cause the Finder to “hang” or fail.
Create a folder on your internal Mac drive (e.g., a folder named Recovery).
Mount the problematic partition again via Terminal.
Run this command to copy the files: sudo rsync -avP /Volumes/j3/ /Users/YourUsername/Desktop/Recovery/
Note: The -P flag allows it to resume if the dodgy USB port disconnects again.
The error -69716 often occurs because First Aid cannot repair a CoreStorage volume while it’s “locked” or in a transitional state. You can try to “revert” the partition back to a standard HFS+ volume, which often fixes the mounting issues.
Open Terminal and type: diskutil cs list
Look for the Logical Volume ID (a long alphanumeric string).
Type: diskutil cs revert [INSERT_LV_UUID_HERE]
This process is non-destructive and attempts to strip the CoreStorage wrapper away, leaving just the HFS+ partition.