topic Re: CFexpress 128GB capacity error on Canon R6 V – Shows "Full" but only 6GB are used in EOS DSLR & Mirrorless Cameras

CFexpress 128GB capacity error on Canon R6 V – Shows "Full" but only 6GB are used

democanty — Fri, 17 Jul 2026 19:00:17 GMT

Hi everyone,

I'm reaching out because I'm experiencing a very specific and frustrating issue with a Lexar silver 128GB CFexpress card on my Canon R6 V.

The Issue: The card is detected perfectly fine when first inserted, and I can start shooting without issues. However, the glitch triggers after recording a few video clips. After a few takes, the camera suddenly stops and throws a "Card Full"error.

The strangest part is that when I navigate to the camera's menu to check the storage or format, the indicator shows that only 6GB out of the 128GB total are actually being occupied. The camera gets locked into thinking it's full, even though there are over 120GB of free space.

Troubleshooting already done:

Ruled out a counterfeit/fake card: I connected the card to my computer and successfully transferred over 100GB of continuous data. The physical capacity is genuine and there are no bad sectors blocking the storage.
Deep Formatting: I have formatted the card on my PC (ExFAT) and also performed multiple Low-Level inside the Canon menu. The issue keeps coming back as soon as I record video again.
Hidden Files: I always empty the system trash while the card is connected to avoid hidden .Trashes folders.

Has anyone encountered this specific issue where video recording triggers a false "Card Full" error? Is it a known firmware glitch or a controller incompatibility with certain CFexpress cards?

Any help would be greatly appreciated!

Re: CFexpress 128GB capacity error on Canon R6 V – Shows "Full" but only 6GB are used

shadowsports — Fri, 17 Jul 2026 20:19:16 GMT

Greetings,

Check directly with Lexar to see if there are any known compatibility issues with the R6v and your card.

Next test with another card. Another brand preferably (if possible)

Last, register your camera in your MyCanon portal and contact support. 1-800-652-2666

Re: CFexpress 128GB capacity error on Canon R6 V – Shows "Full" but only 6GB are used

democanty — Fri, 17 Jul 2026 20:26:15 GMT

Thanks for the advice! I actually already checked Canon's official compatibility list, and the Lexar Silver CFexpress is explicitly listed as fully compatible with the camera. I will go ahead and register the camera to contact support as you suggested, just in case it's a specific camera firmware issue.

Re: CFexpress 128GB capacity error on Canon R6 V – Shows "Full" but only 6GB are used

democanty — Fri, 17 Jul 2026 20:27:18 GMT

It seems like a File Allocation Table (FAT) / Cluster Overhead issue, where the camera reserves a massive block of data for each new video file, and multiple short clips are fragmentation-locking or "hogging" the card's index table, making the camera think it's out of space.

Has anyone else noticed this cluster overhead glitch with short video clips on CFexpress cards? Is there a specific allocation unit size (cluster size) I should format the card with on my PC to prevent this?

Re: CFexpress 128GB capacity error on Canon R6 V – Shows "Full" but only 6GB are used

Waddizzle — Sat, 18 Jul 2026 17:40:40 GMT

Troubleshooting already done:

Ruled out a counterfeit/fake card: I connected the card to my computer and successfully transferred over 100GB of continuous data. The physical capacity is genuine and there are no bad sectors blocking the storage.
Deep Formatting: I have formatted the card on my PC (ExFAT) and also performed multiple Low-Level inside the Canon menu. The issue keeps coming back as soon as I record video again.
Hidden Files: I always empty the system trash while the card is connected to avoid hidden .Trashes folders.

———————-

Nothing wrong with one and two. But number three is a no-no. The only device that should write on the card is the camera. Yes, deleting files is a form of writing to it.

I reformat the card to delete files.

Re: CFexpress 128GB capacity error on Canon R6 V – Shows "Full" but only 6GB are used

democanty — Sat, 18 Jul 2026 18:15:02 GMT

Thanks for the replies, everyone. I want to add some crucial details I just discovered:

I always format both my SD and CFexpress cards directly in-camera before every shoot. However, I just noticed a very specific behavior:

This issue happens almost exclusively when recording short clips in 1080p. When shooting in 1080p, the camera reserves an absolute massive amount of space per clip, completely draining the remaining time counter after a few takes. In contrast, when I record in 4K, the camera behaves perfectly—the counter drops by the exact minutes and seconds I actually recorded.

This makes me believe it's a firmware file-management bug unique to the new R6 V, where the allocation overhead for 1080p is broken.

Is there an official channel where I can formally report this bug? Do Canon representatives or engineers monitor this forum to escalate these kinds of firmware glitches? I'd really like to get this to their development team.

#Canon Moderator #Community Manager

Re: CFexpress 128GB capacity error on Canon R6 V – Shows "Full" but only 6GB are used

jrhoffman75 — Sat, 18 Jul 2026 19:10:36 GMT

You contact canon support at 1-800-OK-CANON and see if they know about it.