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I'm trying to format a SanDisk 16GB microSD card but when I do I keep getting the following message:

One or more partitions are busy on /dev/mmcblk0

How do I correct this so that I can properly format the card? I've tried formatting it with GParted but it never makes it past the second step.

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you can see mounted partitions with the 'mount' comand. And you can unmount one with the umount command in a terminal. or right-click on partition in gparted and choose unmount – solsTiCe Dec 8 '14 at 18:51

try umount it first. Use the new utility that comes with ubuntu , its name is disk utility or something like this.

or try open a terminal and do

sudo mkfs /dev/mmcblk0 -t ext3

or -t vfat if you want to use it on windows

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