Cant write to SD card?

Well, the arm seems to spring in and out no problem, however found this on another thread https://discussions.apple.com/thread/4261016?answerId=19452639022#19452639022, and it solved my read-only issues. Can now read and write throught the SD card slot. Moving the lock slider to an intermediate point did not work for me.

"I removed the back of my Mac just now, and looked at the small gap on the logic board where you can see the SD reader.

On the right hand side (Closest to the first USB port) there is a small silver arm that you can see. I simply pushed it back in with a paper clip, and now my SD reader recognizes the same card as Read/Write."

THANK YOU SO MUCH I bought myself a JetDrive and noticed that ALL SD cards put in would be read only, I tried so many things including resetting SMC, PRAM, alcohol on kitchen towel, blowing inside, inserting cards a little skewed, wiggling, lock switch to middle position, NOTHING worked.

I would like to share exactly how to fix this the way I did, in case anyone else has this issue. For a long time I tried to bend the arm without anything plugged in, however, the arm didn't budge when i poked a paperclip at it. It was too recessed into the card slot enclosure itself to move. I plugged in an SD card in lock position, the pin popped out a little bit, and I managed to get the paperclip to push the arm. Booted up, plugged the JetDrive in and viola!

For future reference, POKE HERE with card inserted, the metal should be accessible because the card lock switch will shift it out.

Boot into Recovery mode. When the OS X Utilities screen appears, select

Utilities ▹ Terminal

from the menu bar. In the Terminal window, type this:

touch /V

Press the tab key. The partial command you typed will automatically be completed to this:

touch /Volumes/

Now type the first few letters of the volume name and press tab again. The name should be auto-completed. If not, type it out. Press return.

If you get an error message to the effect that the volume is read-only, then that's what it is. If you get no error message, the volume is writable, and something is wrong with the system on your startup volume. In that case, you should quit Terminal and reinstall OS X (but only if you have a current backup.)

To exit Recovery mode, select

 ▹ Restart

from the menu bar.

The device is formatted for Windows, as NTFS. The format is readable, but not natively writable on a Mac. To write to the device, you must either reformat it (erasing all the contents) or install third-party software to enable write access to NTFS.

He mean like on a external drive of some kind. Even on a large USB thumb drive. Once OS X is installed on that other device ( external Drive) boot your mac from it and test the SD card reader. If it works then it is your copy of OS X installed on the internal drive. If it doesn't work then it is the card reader.

I can't tell you anything that isn't obvious. There's no secret button to push that I know of. You have these options:

Use the cards read-only on the Mac. If the camera can write to them, I don't see why it's a problem. The purpose of the cards is to store data in the camera and transfer it to the computer.

Write to them on your PC, if you need to to do that for some reason that I'm unaware of.

Try an external card reader (which is cheap, but may not work.)

no, slider is in read/write position (towards the computer). Sliding it in until just before (1-2mm) it stops allows read/write. Anymore and it is read only.

Do you know if that arm is set up so arm-out is read only, arm-in is read/write? By out I mean sticking out into the SD slot, it I mean pressed in towards computer.

I just had this problem, the way I fixed this is by blowing hard 😀 into sd card reader (MBP early 2011).

I noticed that apple ***** at these small things - my thunderbolt port is flickering, my audio out became mono, annoying things happen to sd card reader, usb ports like to disconnect when I push my mbp a little 😟

I have the same problem. But when I read the SD card in a Windows 7 virtual machine mounted on Mac OS X, everything is solved. So this cannot be a hardware fault. It's a software (OS) problem with Mac OS X. Apple, please look into this problem and fix it asap. I really don't like starting the virtual machine everytime when I want to modify the content on my SD card.

I have a similar problem where my Mac is unable to write to or delete files from an SD card in the card reader. Another post from 2010 mentioned changing the "Lock" switch to be halfway between locked and unlocked - and that worked for me! With it in the halfway position, I can now do anything on the SD card. Seems like the reader in MacBooks needs some work.

I just had this problem: SD cards would appear as writable in a cheap reader but not from the SD port on my iMac.

Pushing the card in and out of the iMac SD car slot three or four times seemed to fix it.

I had the same problem with my MacBook Pro 15" mid 2009.

The problem is a dirty or little bend write protection tip/arm on SD card slot.

I had disassemble the motherboard and clean the tip/arm on the side with alcohol and compressed air. Now it works! Not perfect but now I can write two out of five times I put in a SD card.