APFS partition disappeared

Hi all,

I converted a partition on an external disk (HDD) from encrypted HFS+ to APFS (bad mistake 😟).

After some days the partition became read-only and during the backup, it completely disappeared.

FSCK_APFS fails to rebuild.

Here follows some information on the disk from diskutils list:

/dev/disk6 (external, physical):

#: TYPE NAME SIZE IDENTIFIER

0: GUID_partition_scheme *2.0 TB disk6

1: EFI EFI 209.7 MB disk6s1

2: Apple_APFS Container disk7 1.0 TB disk6s2

3: Apple_APFS Container disk8 999.7 GB disk6s3

/dev/disk7 (synthesized):

#: TYPE NAME SIZE IDENTIFIER

0: APFS Container Scheme - +ERROR disk7

Physical Store disk6s2

/dev/disk8 (synthesized):

#: TYPE NAME SIZE IDENTIFIER

0: APFS Container Scheme - +999.7 GB disk8

Physical Store disk6s3

1: APFS Volume macbookpro-tm 914.5 GB disk8s1

The partition disk6s2 is marked as +ERROR in size field.

The APFS Volume is not even shown anymore (it was named macbookpro-external)

When I try to perform fsck_apfs this is the result:

#> fsck_apfs -n /dev/disk7

** Checking volume.

** Checking the container superblock.

** Checking the EFI jumpstart record.

** Checking the space manager.

** Checking the object map.

** Checking the APFS volume superblock.

** Checking the object map.

error: (oid 0x148e92) om: btn: invalid o_type (0x40000002)

Object map is invalid.

** The volume /dev/disk7 could not be verified completely.

Any hint to avoid data loss?

Cheers,

Luke

P.S.:

The external disk has no hardware fault or errors. I checked the SMART metadata, performed the tests

(short and long) and performed a search for bad sectors (no bad blocks found).

It's a perfectly healthy disk with still a long life ahead.