USB formatted as MS-DOS won't open in Windows

Discussion in 'OS X El Capitan (10.11)' started by Randall88, Sep 23, 2016.

  1. Randall88 macrumors newbie

    May 22, 2015
    A USB drive that was working within Windows 10 I couldn't open in Mac.
    So I erased / formatted it to MS DOS Fat... which should be compatible with both OS.

    However, when I now put it back in Windows, this is what shows up..

    Why is this happening, and what can I do ?

    It's quite urgent... thanks!

    Attached Files:

  2. rctlr macrumors 6502a

    May 9, 2012
    Did you format it with a MBR (Master Boot Record)?
    I've found, it's better to do that if you want to swap the USB Drive from OS to OS.
  3. keysofanxiety macrumors G3


    Nov 23, 2011
    Ensure your drive is plugged in.

    1) Open an elevated command prompt. You can do this by right-clicking the Start button at the bottom-left and select 'Command Prompt (Admin)', or whatever is synonymous with that.

    2) Type in diskpart and press Enter.

    3) This will bring up the DISKPART> command prompt.

    4) Type in list disk and press OK.

    5) You will now get a list of disks, numbered.

    6) Figure out which one is your USB drive. For instance, Disk 1. Then type in select disk 1 and press Enter (assuming disk 1 is your drive).

    7) Type in clean and press Enter.

    8) Type in create part primary and press Enter.

    9) Type in assign and press Enter.

    10) You should then get a new dialogue message in Windows saying the disk needs to be formatted. Reformat as FAT32 or exFAT.

    Please let me know if this works. :)
  4. McCloud94 macrumors member

    Sep 9, 2016
    awesome guys, thank you!

    this did the trick. For some reason, I thought I'd choose MBR only when I want a bootable USB.

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3 September 23, 2016