SD Card Repair: How to Fix a Corrupted Card

SD cards stop working for many reasons, including damage, data glitches, and compatibility problems. However, because these cards are designed to be rugged and portable, many data-access problems relate to being used across many (and in some cases, old) hardware platforms, rather than to a defect in the card. An SD card is a cross-compatible storage device. However, devices with incompatible filesystems make it appear that the problem lies with the card and not with the underlying devices.

Causes of SD Cards Not Working

SD cards, in theory, are practically indestructible. These types of storage media tolerate liquid immersion and magnets well. If a card fails to work properly, the odds are good that the problem is a corruption of the filesystem or an incompatibility between the filesystem and a given device or computer.

How to Fix an SD Card Not Working

In many cases, straightforward troubleshooting restores access to the card.

1. Reinsert the card. Removing and reinserting the card, or changing the USB hub into which an SD-card reader connects, often clears any transient glitch.

2. Look for a lock switch. Many SD cards include a side switch that serves as a lock protection. If the device can read from the card but cannot write to it, the switch may be in the locked position. Toggle it.

3. Inspect the card for signs of damage. A cracked housing suggests that the chips inside are damaged. Likewise, missing or corroded contacts on the edge of the card may limit its ability to speak to a device. Clean the contacts with compressed air then reinsert the card, provided it shows no other signs of damage.

4. Check the card for errors. The chkdsk command on Windows reviews a disk's filesystem and, as necessary, corrects errors. SD cards sometimes experience write errors (for example, when the card is removed too soon before a write-from-memory transaction completes) that affect the whole card, but which correct through chkdsk.

5. Reformat the card. A card inserted into a camera or other device supports on-device formatting. A card intended for use on Windows-based computers supports formatting using a Windows-capable filesystem. Reformatting an SD card removes its existing data. If a reformat fails to work, the odds are high that the card is damaged in some way and must be replaced rather than repaired.

   A device may format a card using a filesystem that Windows, macOS, or Linux cannot natively understand. This filesystem incompatibility doesn't reflect a card problem but may be a software challenge between the computer and another device. Reformatting a card into a computer-recognized filesystem may render the card unable to work in that device, and vice-versa.