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stanw

macrumors 6502a
Original poster
Aug 29, 2007
842
5
I am trying to format a SanDisk Ultra 64GB micros SDXC card using an adapter with my 2015 iMac running 10.12

The card will be used in an Android tablet and it was previously formatted inside the tablet, however it was formatted in someway that it will not allow me to copy media to it, so I am trying to re-format it on the Mac.

Using Disk Utility, I tried all of the different options in the formatting drop-down menu
and receive the same error message that it failed and when clicking on details it states:
Unmounting disk
Couldn’t modify partition map.
Operation failed…

Anyone have any ideas what I can do?

Thanks.
 
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