APFS Failed to read superblock, desperate call for help:)

Unfortunately if macOS or Disk Utility is unable to repair the volume then you are out of luck since there are no third party utilities that can repair the APFS file system since Apple hasn't released the necessary APFS documentation.

You should just restore from a backup. If you don't have a backup, then take this as a hard lesson and begin backing up all your important data whether it is on an internal drive or an external drive.

If you can unlock the drive, then you can try using data recovery software such as Photorec, TestDisk, or Data Rescue. Otherwise your only option at this point is to contact a professional data recovery service such as Drive Savers or Ontrack. Both vendors provide free estimates and both are recommended by Apple.

ruudvandermeer wrote:

APFS Failed to read superblock, desperate call for help:)

This was my backup

Why desperate?

3-2-1 Backup Strategy: three copies of your data, two different methods, and one offsite.

Boot clone https://discussions.apple.com/docs/DOC-10081

How to use Time Machine to back up or restore your Mac: https://support.apple.com/en-us/HT201250

Use DiskUtility Restore feature https://support.apple.com/guide/disk-utility/restore-a-disk-dskutl14062/mac

note: >System Preferences>Security & Privacy >Privacy>Full Disk Access

unlock the padlock, press the + button and add Disk Utility

ruudvandermeer wrote:

This was my backup

Then I highly recommend contacting one of the professional data recovery services I mentioned since if you try to "fix" it yourself you will most likely cause more damage which even a professional data recovery service may not be able to do anything about.

Unless you need to recover a file from the backup you should just erase the whole drive as GUID partition and MacOS Extended (Journaled) and start over on your backup.

If you do need to recover a file from the backup and you still want to try it yourself, then you should perform a bit for bit clone of the external drive which will require another drive of equal or larger size. You can use "dd", but I prefer using GNU ddrescue since it can resume an interrupted clone if you use the logging feature. Be very careful since you could easily destroy all data on the original drive if you use the wrong drive identifiers. After the clone is complete then disconnect the original drive to keep it safe.

If the drive is encrypted then use "diskutil" to unlock the encryption on the external clone drive. You can try mounting the clone drive as read-only using "diskutil".

You can try recreating the partition table by restoring it from the backup copy (make sure to replace "diskN" with the drive identifier for the external clone drive):

sudo  gpt recover  /dev/diskN

If that doesn't help, then try TestDisk, PhotoRec, and other data recovery software on the clone to see if any of them can access your file. Keep in mind TestDisk may try to make changes to the drive so proceed carefully or you may need to perform the bit for bit copy again.

FYI, you should not be using APFS on external drives especially for a backup as APFS is a new file system with lots of growing pains.