I'm using a Canon 600D for photoshoots and went to back up images of my last few practice sessions. Using a USB SD card reader, the files in the image below made themselves apparent.

I'm not sure if this is corruption in the SD card or a read error on the SD card reader, but it's strange that there's a 2 GB file there too. I've made a backup of all the other photos and they seem fine, just these strange things. I can't actually navigate into the folders, it just pops up with an invalid format error.

Should I back up and format, or is it safe to just clean these out? The card reader is a cheap brand one that we've started using from the last week, but the SD card we've used for a few years now and haven't noticed anything like this before.

Strangely named folders and files. Bottom of the DCIM folder, two more large strangely named files.

  • I have a similar issue with my SD card.In My case data is very important. How i can recover my data back???
    – Mayur
    Oct 4, 2018 at 11:02
  • @Mayur Have a search on this site for recovering corrupt cards. Maybe start here: photo.stackexchange.com/questions/3323/…
    – MikeW
    Oct 4, 2018 at 18:01

4 Answers 4


Looks like a corrupt SD card to me. Whether or not a format will fix it I can't tell, but from my experience it's a good practice to format the memory card in camera, preferably before each shoot.

  • Thanks! In the end I tried to back up / specifically delete the data but, again, Windows did not agree with the file/folder names. I formatted the card and everything seems to be in order.
    – Sean
    Feb 19, 2017 at 15:37
  • This indeed looks like corruption, especially the incoherent filesizes and dates. Backup what you can and format is the way to go.
    – BiAiB
    Oct 4, 2018 at 12:50
  • 1
    I'd consider it good practice to toss that card away unless it is an exceptionally expensive type. Aug 13, 2019 at 2:03

One option I haven't seen mentioned is systematic corruption by forged memory cards. If you are using cards that have been suspiciously affordable at the time of purchase, chances are that their controller has been tampered with to report an illusionary memory size. Those cards appear to work until you exhaust their actual capacity after which additional writes destroy existing data and directory entries.

Somewhat less drastic failure modes are to be expected from cards that have not passed factory tests and have been brought into circulation instead of being destroyed.

There are test programs for the first kind of manipulation and you should use them before entrusting the card with data you consider important.


Rather than straight corruption, this looks like a copy of encrypted or compressed data. This can have arisen from multiple sources - computer backups; files encrypted for security; or a virus. The answer provided by @Kamen Minkov is the best way forward.


There are 2 possibilities here:

  • it appears your card has some junk folders and files. That could be that your SD card is not brand new. That it was used.

  • It's files left by backup / encryption program, some other tools that recently worked on your SD card.

If you're sure you don't need the folders/files anymore, you can always format it after backing up the important image files.

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