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SD card cannot be read in EOS Rebel T7


I have a Canon Rebel T7, a 256mb SD card (full size not micro,) and a Mac.

When I use an adapter and plug the card in it says, “this disk inserted was not readable by this computer.” If I reformat it on my Mac then my camera says that it can’t read the card and I have to format the card on my camera. If I format the card on my camera then my Mac gives the same not readable message. I’ve done so much googling I can’t find an answer!

I’ve tried two different brands of 256mb SD cards. The only card that works on both my camera and Mac is an old 4mb card I’ve had for years.


Is the card size too big? Do new SD cards require a different card reader? (My reader is years and years old. I had been using a Mark II for 14 years and it just died and I’m unable to afford to upgrade.)

It’s been a giant headache as I photograph a service every Sunday and I now have to transfer my photos onto my mom’s PC to a flash drive to get them onto my Mac to edit. She’s only visiting so once she leaves I can’t access my photos. Please help me before I pull my hair out!



Not going back to read all the replies but....noticed the card is formatted on the Mac. Format in the camera.

Canon EOS T7; EF-S 18-55mm IS; EF 28-135mm IS; EF 75-300mm; Sigma 150-600mm DG