My Passport for Mac (2013) can only read - not write

My passport for Mac P/N WDBZYL0020BSL is used on my MBP with OS version 12.0.1. I make backups with Time Machine. Today this failed with the text that writing was not possible and I had to make a copy and reformat the disk. That failed with the Apple disk program with the note that the disk could not be deactivated. I downloaded the WD utilities. The diagnoses was OK and the quickest was OK. Reformatting however failed again. Does anybody here have an idea about this?

Might be time for a Mac friendly NAS unit and then migrate to the NAS

Thanks for your reply. Any suggestion for a Mac friendly NAS unit?

The following worked for me in Mac Monterrey

  1. Reboot to Recovery Mode by hitting the power button then holding down CMND R.
  2. Open Disk Utility from main screen when in Recovery Mode
  3. Highlight the external drive
  4. Click on Edit at the top.
  5. Click on Erase
  6. Erase the drive
  7. Click Edit again
  8. Click Delete APFS Volume (or whatever format your disk is in)
  9. Select file format Mac Journaled
  10. Name the drive
  11. Reformat the drive
  12. Restart the computer

Thanks Brian, I did manage to format the drive but now I can only make back-ups with Time Machine. When I want to add another map to that drive it forbids that. Before these troubles I could make back-ups and add whatever I wanted. Any idea what might be wrong?