I'm using Lion (10.7.3) on a mid-2010 MacBook Pro. I just got a 32GB SD card and formatted it with my camera. I'd like to transfer some files onto it from my computer, but the card seems to be read-only when I access it in Finder. And in Disk Utility, all options are grayed out so I can't reformat the card.

I found this KB article which seems to describe the problem, but the solution doesn't work:

$ diskutil partitiondisk disk1 JHFS+ newdisk 100%
Started partitioning on disk1
Unmounting disk
Error: -69877: Couldn't open device

What's going on and how can I get around it?

Edit: yes, I already checked the physical lock switch on the card!


I was just going to suggest the lock switch too... but if that's not it, can you click the Partition tab and tell us how the card is currently formatted? If I remember right, OS X can read but not write an NTFS-formatted device, but it seems unlikely that your camera would have formatted the card that way.

  • 1
    It's shown as "MS-DOS (FAT)" as in the first screenshot. – jtbandes Feb 14 '12 at 15:52

I encountered the exact same thing... the issue was that the lock switch was getting flipped when I pushed the card into the slot and it would flip back to unlock when I pulled the card out, lol. I was able to get it in without the switch flipping by pushing it to the opposite side of where the switch is.


The only other time I've seen this is when the card was locked. Did you accidentally hit the lock mechanism on the corner of the card?

  • Forgot to mention that I already checked this. Thanks though. – jtbandes Feb 14 '12 at 15:50

Unfortunately I'm not sure what the problem was — after some more formatting and fiddling around, the issue resolved itself.

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