My 6D has been working fine until recently. Then a Sandisk 128GB SDXC card I had been using for a year stopped working. OK, card fail that's fine. I bought it on vacation, so it might be a fake or of questionalble origin.
I continued using my 6D with a Sandisk 200GB SDXC card. It worked normally for a month or two, and then today the camera said it couldn't read the card. I had left the camera turned on for a week or more and the battery was low. I changed the battery but the card was still unavailable to the camera. I pulled the card, and Lightroom could read it fine. Put the card back in the 6D, tried to format it, and it failed. I couldn't do a low level format becase the controls were frozen while the camera was trying to access the card. And after the format failure Lightroom couldn't read it any more.
I tried an older Sandisk 32GB SDHC card that has never let me down, and the camera reported that it couldn't be read as well. So now I had three dead Sandisk cards of various sizes, speeds, origins...
My PC couldn't access the cards to reformat them, so I can't even try to update the camera's firmware (it's two versions behind) because the 6D can't read SD cards.
Last ditch effort - I pulled out my 6DMKII, and while it was not able to do a quick format, it could do low level formats on the two SDXC cards. The SDHC card is still dead.
So now I can use the biggest two of the three cards in the 6D, but can I trust my 6D anymore? Will a firmware update address this problem specifically? There's nothing in the notes to indicate that it will. Could the camera's SD card contacts inside be dirty and not communicating with the cards properly? Are there SD slot cleaning tools available?
I should mention that these are micro SD and I'm using two different adapters, all with the same results, so I don't think it's an adapter problem.
