Cant write to SD card?

I am also having this problem. I have several new SD and they all are read only at this point. I card that stopped working first had the lock/unlock arm come off. So I am wondering if piece is stuck in behind the arm in the computer. I put an external SD card readers and new card works in SD reader. New SD card will not work in the computer SD slot. Any body ever dug this deep in the machine? I have replaced memory, processors and disk drives, but never gone this deep into it.

I'm having this same problem pretty much as described above, except that I did plug it into the card reader on my Epson Printer (hooked to my Macbook Pro (2012) via apple monitor USB and into the Macbook USB.

Same problem. Both SD cards I'm testing with are only readable and I can't seem to do anything to effect change. They are both formatted via a Nikon and one of them I just reformatted (no fancy options to choose from in-camera, just plain "FORMAT".

So this seems like a software issue to me unless a faulty arm inside the macbook is somehow causing all SD cards (even through a USB) to also misread the write status.

Very perplexing and especially based on how common this issue seems to be (there are lots of similar threads) and that no one has identified some kind of missing file or patch or something.

This computer is relatively new to me and it had one version of OSX and the I restored from my old Macbook Pro (late 2010) after updating it to Mountain Lion. So could the restore have brought over some incorrect file from the old hardware/software configuration?

I don't know enough to answer that.

p.s. The reason I need to write to the card is that this is how to update the firmware. It seems I have to do it. Also, one should be able to write to one's men cards as a rule.

This is so frustrating

Thanks for any advice from anyone.

In that case, your card reader is probably malfunctioning. To be sure, you would have to cleanly install OS X on another device, boot from it, and test.

You can boot into Recovery mode and test the card in the shell. Ask if you need instructions.

What is the name of the volume on the card?

There is no switch in the reader. The switch, if there is one, is on the card. A reader costs about $10, maybe less.

TacoLord187, how did you get the arm to stay there? Presumably it sprang back? I've got the same problem, works fine in the iMac, but in the Macbook it is read only.