macOS has a very dumb ExFAT driver compare to the one on Windows. The mac driver currupts ExFAT formatted portatable drive very often and take forever to repair. Bootcamp into Windows was my only option to clean currpted ExFAT hard drive. Now with exfat_clean you can solve this in under 1 second :)
This may result in data loss, only use it if you are 100% sure the driver is being dumb and the hard drive is not actually corrupted.
- Find out your hard drive's ID
$ diskutil list
... (skipped)
/dev/disk2 (external, physical):
#: TYPE NAME SIZE IDENTIFIER
0: FDisk_partition_scheme *1.0 TB disk2
1: Windows_NTFS Portable Drive 1.0 TB disk2s1
- Now fix it
$ ./exfat_clean /dev/rdisk2s1
Note we are using the raw disk id for the partition rdisk2s1
Long story short in the ExFAT partition header there is a bit called dirty bit. This program changes dirty bit to clean so the system assume the drive is already repaired (it was never broken to began with)