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SSD disappeared from Disk Utility and Finder after format failure

My 2015 Macbook Pro running macOS Mojave is almost out of space. So I took the SSD used on my Windows laptop and plugged it into my Mac. Since I'm saving my personal data, I want to encrypt it. I went to Disk Utility to reformat the NTFS file system into APFS Encrypted, which failed with an error indicating not having enough space on the selected drive. I then chose Mac OS Extended (Journaled), but it made the SSD disappear from both Finder and Disk Utility. Strangely, when I connected it to the Windows PC, the SSD showed up but in a non-formatable state.

Best Answered by

Jenny Zeng

Answered on Monday, April 29, 2024

Your SSD has likely failed, as it won't format on your Mac or Windows PC.

Before replacing it, try reformatting the external SSD with diskpart, as described in the following steps:

  1. Click Start and type cmd.
  2. Choose to "Run as administrator."
  3. Run the command below to open diskpart.diskpart
  4. Check the disk number of your SSD.list disk
  5. Select the SSD. (e.g., select disk 2)select disk number
  6. Clean the external drive.clean
  7. Create a primary partition.create partition primary
  8. Format the drive to NTFS.format fs=ntfs
  9. Assign a drive letter.assign