Windows 7 cannot see Exfat drive

gtvmark 1 Reputation point
2020-10-20T00:11:35.903+00:00

I have a 64gb usb drive, formatted in a windows 10 machine, works correctly on Windows 10, and linux and macos, but windows 7 sees the partition as a fat32 drive and won't assign a drive letter.

There was mention of a KB download, kb955704 but I think that's for XP.

Can anyone suggest anything?
(ps sorry for the irrelevant tag, I couldn't find any tags mentioning filesystems, usb drives or exfat)

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  1. Dave Patrick 426.1K Reputation points MVP
    2020-10-20T00:25:15.427+00:00

    Something here may help.
    https://learn.microsoft.com/en-us/openspecs/windows_protocols/ms-fscc/d4bc551b-7aaf-4b4f-ba0e-3a75e7c528f0

    --please don't forget to Accept as answer if the reply is helpful--

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  2. Jenny Feng 14,111 Reputation points
    2020-10-20T02:12:57.913+00:00

    @gtvmark
    Hi,

    FAT has great limitations.
    Unless you are trying to share and write files between different base OSs I would reformat the external drive to NTFS and then use it.

    If you find that Windows cannot read the partition, you will need to reformat it in Windows.

    Hope above information can help you.

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  3. gtvmark 1 Reputation point
    2020-10-20T05:21:21.697+00:00

    I'm using Windows 10, Linux, Macos and Windows 7, so NTFS is out of the question. I am aware that formatting drives on other OSes can have unexpected errors, hence I originally formatted the drive on Windows 10.
    I've run CHKDSK on windows 10, which says there is nothing wrong with the device and nothing to do.
    All OSes agree on the block where the partition starts on the drive, via WMI win32_diskpartition and a number of disk recovery tools. I've looked at that block, and it certainly looks like an EXFAT header. I don't know why windows 7 recognises it as Fat32.

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  4. gtvmark 1 Reputation point
    2020-10-20T06:58:05.377+00:00

    I've discovered why windows 7 does not see this partition, because it is unable to handle a second primary partition on a disk. With an MBR partition drive this is ok because the second partition you make becomes a logical partition in an automatically created extended partition. But with GPT, which supports 128 primary partitions, any second partition you make will also be primary and Windows 7 will only ever recognize the first partition. My USB drive had a 200meg EFI system boot as its first primary partition which windows 7 identified as fat32, but the real data was in the second ExFat primary partition. It doesn't matter what filesystem it is, I did try formatting it to NTFS and windows 7 still would not see the second partition.
    Even windows 7 disk manager had all sorts of problems with it, It can show that there is a partition there, but can't identify it, delete it, format or modify it in anyway. Not even windows 10 disk manager will allow you to modify a "system" partition.
    Fortunately I've access to tools that allowed me to delete the EFI partition without touching anything else on the drive and now my files are visible on windows 7.