Mac OS High Sierra diskutil eraseDisk 导致错误：-69877：无法打开设备

Question

I am having issue converting a new SanDisk 128GB microSD card from ExFAT to FAT32

$ diskutil info /dev/disk2

  Device Identifier:        disk2
   Device Node:              /dev/disk2
   Whole:                    Yes
   Part of Whole:            disk2
   Device / Media Name:      Built In SDXC Reader

   Volume Name:              Not applicable (no file system)
   Mounted:                  Not applicable (no file system)
   File System:              None

   Content (IOContent):      FDisk_partition_scheme
   OS Can Be Installed:      No
   Media Type:               Generic
   Protocol:                 Secure Digital
   SMART Status:             Not Supported

   Disk Size:                127.9 GB (127865454592 Bytes) (exactly 249737216 512-Byte-Units)
   Device Block Size:        512 Bytes

   Read-Only Media:          Yes
   Read-Only Volume:         Not applicable (no file system)

   Device Location:          Internal
   Removable Media:          Removable
   Media Removal:            Software-Activated

   Virtual:                  No

Here is the mounted partition

$ diskutil info /dev/disk2s1

Device Identifier:        disk2s1
   Device Node:              /dev/disk2s1
   Whole:                    No
   Part of Whole:            disk2

   Volume Name:              
   Mounted:                  Yes
   Mount Point:              /Volumes/Untitled

   Partition Type:           Windows_NTFS
   File System Personality:  ExFAT
   Type (Bundle):            exfat
   Name (User Visible):      ExFAT

   OS Can Be Installed:      No
   Media Type:               Generic
   Protocol:                 Secure Digital
   SMART Status:             Not Supported
   Volume UUID:              555AF300-2369-3CE8-B4E1-D8F976CE9C86
   Partition Offset:         16777216 Bytes (32768 512-Byte-Device-Blocks)

   Disk Size:                127.8 GB (127848677376 Bytes) (exactly 249704448 512-Byte-Units)
   Device Block Size:        512 Bytes

   Volume Total Space:       127.8 GB (127831900160 Bytes) (exactly 249671680 512-Byte-Units)
   Volume Used Space:        393.2 KB (393216 Bytes) (exactly 768 512-Byte-Units) (0.0%)
   Volume Free Space:        127.8 GB (127831506944 Bytes) (exactly 249670912 512-Byte-Units) (100.0%)
   Allocation Block Size:    131072 Bytes

   Read-Only Media:          Yes
   Read-Only Volume:         Yes

   Device Location:          Internal
   Removable Media:          Removable
   Media Removal:            Software-Activated

First I unmount:

$ diskutil unmountDisk /dev/disk2
Unmount of all volumes on disk2 was successful

Then I erase the disk and format it to FAT32

$ diskutil eraseDisk FAT32 NEW_NAME /dev/disk2
Started erase on disk2
Unmounting disk
Creating the partition map
Error: -69877: Couldn't open device

How can I erase the disk and format it to FAT32 without using third-party applications?

Answer 1

I found I had to unmount the logical drive first, then I could delete the drive.

a) select the logical drive

b) unmount

c) select hard drive

d) erase