SanDisk Ultra SD card will not work with canon 70D

[Aimless]

A while back I got a 256 gb SanDisk ultra and that worked for a year just fine. Then recently when I started messing around with magic lantern the card stopped working. Even after formatting, the card "bricks" my 70D. When the card is put in, the camera stops working. No lights, no errors, no buttons, no nothing. The only way to get it back is take out the SD and the battery. That was my only card at the time so I bought a 128gb SanDisk ultra to replace it. While waiting for it to arrive I found an old 256mb SD impact that I retried ML with and it worked just fine. Then I found a topesel 128 gb micro sd and put it into and adapter which also worked. When the New SanDisk arrived I put it in the camera straight out the box and it had the exact same problem as the 256gb one. Both the micro and the Sandisks say they are SDXC. Can I fix this? Do I just need different SD cards? which ones do I need to get?

[normadel]

1. A universal recommendation is to NOT use micro SD cards. They can be troublesome . Use full-size SD cards only.

2. 128 and 256 GB SD cards are huge. Cards this large can sometimes be troublesome. Beside that, it's not a great idea to use cards this large. It makes it too tempting to store your photos on the SD card long-term, which is dangerous. If the card fails or becomes problematic, you lose everything. 

A 32 GB card, what I use, will hold  thousands & thousands of images. Do you want to risk a loss like that?  Use multiple cards, swapping one one out of the camera until you move files to a computer/external storage. Then format it in the camera. Do low-level formats occasionally.

There's a program for Windows and Macs called "SD Card Formatter", from the company that develops the SD card standards.  It "conditions" an SD card so its structure is up to snuff. Get it here:

https://www.sdcard.org/downloads/formatter/

Use it on your SD cards occasionally, then format the cards in-camera.

[Aimless]

I get they are too big and will avoid buying ones this big in the future but is it possible to get the 2 I have now working? I tried low level formatting and the SD card formatter to no avail on both cards.

[normadel]

If it is only two of your cards, then there must be something about them the camera just doesn't like. Maybe others can offer something.

[Peter]

Did you reset the bootflag? Else you will hang the camera when you use a bootable card.

[normadel]

How/where do you do this?  Haven't heard of it before.

[Peter]

OP mentioned Magic Lantern. A common mistake is to just remove Magic Lantern from the card instead of uninstalling it from the camera.

 

[Walter_Schulz]

Peter is correct:
"Uninstalling" ML requires running the install process once again. After installation message appears you will see a timer at the bottom counting down from 60. After timeout sets in cam will be clean. The thing which may cause confusion is a so called "boot flag". Your cam has enabled it.

Without proper uninstallation cam will do this at startup (and a bit before) and during wake up from powersave:
- Access card and check if the card is bootable
- If a bootable card is found cam will try to locate autoexec.bin and load it during startup.If autoexec.bin is not found -> stall cam without error message. You have to remove battery to un-stall.

There are at least 2 conditions where an error like you may happen:
- Card unaccessible/unreadable. Short explanation: A cam *without* boot flag set will throw an error message if card is unreadable. For example: Insert microSD adapter without microSD card. 
A cam with bootflag set is unable to show an error message. Cam will just stall! 
This may throw off service staff a bit.

To un-stall your cam you can do this:
- Remove card and battery
- Copy Magic Lantern files and directories/folder to card.
- Prepare card using EOScard Utility (for Windows only)
-- Run EOScard as Admin ...
-- Make sure to have your card drive selected!
-- Check again! 😉
-- Mark boxes EOS_DEVELOP and BOOTDISK
-- Press Save button
- Insert card
- Close card compartment door
- Insert battery
- Close card compartment door
- Startup cam and access "Firmware update"
- Run Firmware update
- Wait for 60 seconds after install message appears. A new message will appear telling you deinstallation is complete.

Well, that's not complete but you should have no troubles during startup anymore. To avoid confusion you should re-format the card you used for deinstallation.

If you are *not* running Windows or have any troubles: Access Magic Lantern Forum and follow the Discord invite. We will be able to guide you and I'm pretty sure we can fix your issues.

(And I'm not the only person using microSD with ML and cards from 512 KB to 512 GB)