my t4i will not read any SD cards

[evanjamesmommy]

When I try to take a picture, it says: "Card cannot be accessed.  Reinsert/change card or format card with camera."

So, I try to format the cards, and it says "Cannot format.  Change card."

I have used both these cards before and never had a problem, this just happened all of the sudden.

I even tried re-formatting the cards on my computer, but no luck.

[erikborgo]

I also have this problem with the T4i.  It's been getting progressively worse and now it won't recognise any of my SD cards, or new ones listed as compatible.  What do Canon do to repair this?  Has anyone managed to fix this themselves?  I've tried keeping the camera in an airtight bag with moisture absorbing silicone beads for two weeks, in case moisture ingress was causing the issue.  I also tried cleaning the SD card and SD card slot pins with 90% isopropyl alcohol, to no avail.  It's surely out of warranty by now - it'd be cheaper to buy a working used T4i or 700D for less than what Canon would charge me for a repair.  I may open the camera to see if there's any physical damage to the pins inside the SD card slot next.  I really don't see why this great camera should be added to yet another gigantic electronic landfill poisoning our soil and water supply.

[erikborgo]

Solved! It was dust! And possibly cat hair - after the umpteenth time inserting, ejecting and reinserting the SD card... After having some success, but failing to get it working consistently by cleaning the contacts yet again using 90% isopropyl... I noticed a small ball of fluff had worked it's way up and out of the slot. Shining the bright focused beam of a bright LED torch into the slot, to inspect using the 2X optical zoom lens of my Oneplus 5 phone, I saw more accumulated fluff. After turning the slot upside down and blasting air into the slot using an air duster (short blasts), cards are recognised again! No I/O errors reocrding videos either - I was only previously only able to record a few seconds of video, and never longer than 30 seconds. It still takes two or three reinsertions for the card to be recognised, but the situation is much improved. Hope this helps someone else.

I'm glad I didn't have to resort to disassembling the camera, because there are often worrying screws, nuts, bolts etc. left over whenever I do that lol. I think any fix using isopropyl or WD40 (there's a Youtube video showing that works) is a temporary one - all any fluid will do is facilitate easier movement of dust and microscopic strands of material away from the contact points between the SD card slot contacts and SD card contacts.

I'll update this thread if this solution ceases to work