I had to encrypt an external backup volume while traveling. Unfortunately, now the drive will not mount. It shows up in diskutil and RepairVolume shows the volume being OK. Despite the passphrase being stored in my Keychain, however, I am still prompted for it and providing the passphrase does not cause the disk to mount, nor does the 'mount' button in disk utitlities. Repair Volume shows the volume being OK but does not officially 'finish' (progress bar continues scrolling.)
dxxx ~ $ diskutil list /dev/disk0 (internal): #: TYPE NAME SIZE IDENTIFIER 0: GUID_partition_scheme 500.3 GB disk0 1: EFI EFI 314.6 MB disk0s1 2: Apple_APFS Container disk1 371.0 GB disk0s2 3: Microsoft Basic Data BOOTCAMP 128.4 GB disk0s3 4: Windows Recovery 505.4 MB disk0s4 /dev/disk1 (synthesized): #: TYPE NAME SIZE IDENTIFIER 0: APFS Container Scheme - +371.0 GB disk1 Physical Store disk0s2 1: APFS Volume Macintosh HD 341.2 GB disk1s1 2: APFS Volume Preboot 47.6 MB disk1s2 3: APFS Volume Recovery 510.3 MB disk1s3 4: APFS Volume VM 1.1 GB disk1s4 /dev/disk2 (external, physical): #: TYPE NAME SIZE IDENTIFIER 0: GUID_partition_scheme *5.0 TB disk2 1: EFI EFI 209.7 MB disk2s1 2: Apple_APFS Container disk4 4.9 TB disk2s2 3: Microsoft Basic Data POISK 127.8 GB disk2s3 /dev/disk3 (external, physical): #: TYPE NAME SIZE IDENTIFIER 0: FDisk_partition_scheme *63.9 GB disk3 1: DOS_FAT_32 BUDrive 63.9 GB disk3s1 /dev/disk4 (synthesized): #: TYPE NAME SIZE IDENTIFIER 0: APFS Container Scheme - +4.9 TB disk4 Physical Store disk2s2 1: APFS Volume Kosmos 4.4 TB disk4s1 Tue Oct 29 10:55 AM dxxx ~ $ diskutil RepairVolume disk4 Started file system repair on disk4 Repairing storage system Performing fsck_apfs -y -x /dev/disk2s2 Checking the container superblock Checking the EFI jumpstart record Checking the space manager Checking the space manager free queue trees Checking the object map Checking volume Checking the APFS volume superblock The volume Kosmos was formatted by hfs_convert (945.275.7) and last modified by apfs_kext (945.275.7) Checking the object map Checking the snapshot metadata tree Checking the snapshot metadata Checking the extent ref tree Checking the fsroot tree Verifying allocated space The volume /dev/disk2s2 appears to be OK [\ \ \ \ \ \ \ \ \ \ \ \ \ \ \]
I realize the very likely outcome is 'reformat disk' but there are a few files which travel logistics meant are not backed up, so if anyone has solved issues with encrypted apfs disks and has suggestions, I thought it worth asking first. Thanks so much!