gParted > FAT32 formatted USB is not recognized in Windows 10

Question

I've tried several times now. I format a 120GB USB3.0 drive as FAT32 using gParted in Ubuntu(from a live USB) then when I try and mount in Windows 10 it doesn't mount. I then open Disk Management and have no option but to reformat the RAW partition as ExFat.

What could cause the gParted FAT32 parition to not be recognized in Win10?

Answer 1

There is a bug in some versions of libparted that fails to preserve the file system boot sector code when resizing a FAT32 partition. I assume that you may have resized the FAT32 partition.

See Bug 759916 - fat(32) resizing generates boot sector(s) with invalid jump instruction and pseudo-random boot code

For Windows to recognize FAT32, it needs the initial bytes (at least 3 bytes "eb 58 90") set as follows:

$ sudo hexdump -n 7k -C /dev/sda1
00000000  eb 58 90 4d 53 57 49                              |.X.MSWI|
00000007

To work around this issue after it has occurred, use a hexeditor such as hexedit to set the initial 3 bytes of the FAT32 file system at the start of the partition.