Mac Catalina - Disc Utility error -69499 - Pls Help!

  • 5 TB My passport ultra for Mac P/N: WDBPMV0050BSL– 0 D
  • Original format 256GB as OS Extended (journaled) for OS files, and the rest as ExFAT (for all documents, etc). Planned to backup 256GB SSD (APFS encrypted) OS to OS Extended, and all apps/data to ExFAT (assumed this is possible).

GOAL (Open to discussion!)
This is how the problem (below) was created. I wanted to downgrade from Catalina to Mojave. I want to clean install Mojave to support 32 bit apps, and restore all applications/data. Why? I learned Catalina only runs 64 bit apps and I want to run some older games. Also, I installed an app but it was a hack and changed Safari to force (and lock out changing) home page. But due to the problem (below), am afraid to keep trying for APFS (so Carbon Copy can make backups).

PROBLEM
Got this WD just a few days ago. After Time Machine failed (does not like OS Extended?), I learned Carbon Copy wants APFS. I tried to erase/format OS Extended to APFS but got error (below). I tried other options I can’t recall, but luckily got back the Extended (journaled) partition.

PICS

  • Pics have same time-stamp but one shows ExFAT, the other shows “unknown”. Also, I can’t do First Aid (greyed out right now).

Partitioning disk “WD My Passport 260F Media” (disk2)

Running operation 1 of 3: Erase “Untitled” (disk2s2)…
Unmounting disk
Erasing
Initialized /dev/rdisk2s2 as a 238 GB case-insensitive HFS Plus volume with a 24576k journal

Mounting disk
Creating a new empty APFS Container
Unmounting Volumes
Switching disk2s2 to APFS
Creating APFS Container
An internal error has occurred. : (-69499)

Operation failed…

Hi,

You could refer to the following link: External Drive: Convert to Apple File System (APFS) Format