Why do SD cards suddenly stop working?

SD cards are incredibly useful for storing photos, videos, documents, and other files on cameras, phones, drones, and other devices. However, it can be incredibly frustrating when an SD card suddenly stops working and refuses to be read by your device. There are a few key reasons why this happens.

Corrupted File System

One of the most common reasons an SD card will suddenly stop working is because its file system has become corrupted. The file system is essentially the card’s “table of contents” that tells the device where all the files and data are located on the card. If this critical data gets corrupted or damaged, the device is unable to make sense of the card’s contents.

There are a few ways an SD card’s file system can become corrupted:

  • Improperly ejecting the card – Always use the “Safely Remove Hardware” function
  • Power loss or sudden removal while writing data
  • Exceeding the card’s storage limits
  • Using the card in different or incompatible devices
  • General wear and tear over time

Severely corrupted cards may be irreparable. But formatting the card using the SD Association’s official SD Formatter tool can fix mild corruption in some cases by creating a fresh file system.

Physical Damage

SD cards have delicate electronics inside that are vulnerable to physical damage. Dropping the card, getting moisture inside, or bending the card can all cause physical damage that makes the card unreadable. The damage can include:

  • Broken or disconnected controller chip
  • Scratched memory chips
  • Snapped/broken pins or contacts
  • Cracked solder

Unfortunately, there is no DIY fix for physical damage on an SD card. The card will need to be taken to a data recovery service if the data is valuable enough to warrant the high costs of repairing it.

Card Errors

SD cards keep track of potential errors or issues that occur through built-in error-checking algorithms. When the card determines that critical errors have built up, it will go into a locked read-only mode to protect the data on board and will appear unreadable to devices.

This failsafe lock mode is triggered once error totals exceed thresholds for:

  • Bad memory blocks
  • File system issues
  • Hardware defects

Reformatting the SD card should clear these error totals and reset the card to a usable state. Back up any needed data first, as formatting erases everything on the card.

Manufacturer Defects

In rarer cases, SD cards stop working due to flaws or failures in their design or manufacturing process. Cards made from subpar materials, contaminated chips, shoddy circuit board assembly, inadequate quality control, and other issues can essentially make them defective “lemons” right out of the box.

Telltale signs of an outright defective SD card include:

  • Never working properly, even when brand new
  • Frequent read/write errors and problems
  • Visibility shorter usable lifespan
  • Issues with cards from a specific brand or production batch

Dealing with a defective card is frustrating, but often the only recourse is to replace it under warranty if possible and switch SD card brands/models.

Counterfeit Cards

There is a thriving black market for fake, knockoff SD cards that are often made from scrap chips and failed materials repackaged to look like major brands. These counterfeit cards initially seem to work and may even have falsified specs printed on the labels.

However, they tend to become corrupted, unreadable, and unreliable very quickly. The low-grade NAND memory chips inside also make them slower than authentic cards.

Watch out for SD cards that:

  • Are generic unbranded cards sold very cheaply
  • Have typos or misspellings on the label
  • Look slightly different from normal cards
  • Come from sketchy sellers and marketplaces

Stick to reputable established brands like SanDisk, Samsung, and Kingston when buying SD cards to avoid getting scammed by counterfeits.


SD cards can unexpectedly stop working for a variety of reasons. The most common causes are file system corruption, physical damage, accumulated card errors, manufacturer defects, and counterfeiting. Reformatting, replacing the card, and checking for fakes can resolve many of these issues. But unreadable cards often require professional data recovery to attempt to salvage their contents.

To minimize the chances of your card failing unexpectedly:

  • Buy cards only from reputable brands and sources
  • Handle cards carefully to avoid physical damage
  • Always eject the card properly before removing it
  • Avoid overfilling cards or using in many different devices
  • Be aware cards have a finite lifespan and replace occasionally

Taking proper care of your SD cards and following safe usage practices will help keep them working reliably for many years.


Here are some references used as sources for this article:

Frequently Asked Questions

Why does my SD card say it needs to be formatted?

If an SD card is showing up as needing to be formatted, it usually means the file system has become corrupted. Trying to format the card using the SD Association’s formatter tool may fix the corruption. If formatting does not work, the card is likely physically damaged or defective.

Can damaged SD cards be fixed?

SD cards with minor file system corruption can potentially be fixed by reformatting the card. But SD cards with physical damage to the memory, controller, pins, etc require specialist data recovery service to attempt repairs, which can be expensive.

Why does my phone say SD card blank or unsupported?

Those error messages indicate the phone is unable to read the SD card properly. This usually happens when the card’s file system is corrupted, or less commonly when there is physical damage. Trying another device, reformatting the card, or replacing it can help resolve the issue.

Why does my SD card keep stopping working?

Frequent SD card failures likely mean it is defective and needs to be replaced. Consistently experiencing problems with multiple cards from a specific manufacturer may also indicate a bad production batch. Buying cards from reputable brands reduces the chances of getting lemon cards.

Can I recover data from a damaged SD card?

Specialized data recovery services may be able to rescue data from physically damaged cards, but the process is expensive with no guarantee of success. Reformatting damaged cards will make the data unrecoverable, so this should only be attempted after backing up whatever data can still be accessed.

Should I store photos on SD card or hard drive?

Storage Benefits Drawbacks
SD Card Smaller size, portable Less storage, more prone to damage
External Hard Drive More storage capacity Larger size, needs power source

For portability, SD cards are handy for photos on the go. But for a home photo archive, external hard drives store vastly more with less corruption risk. Using both provides redundancy in case one storage medium fails.

Why is my 64GB SD card showing much less space?

Storage capacities listed are unformatted gigabytes, while operating systems show the actual formatted capacity which is always lower. Formatted capacities also use binary units like mebibytes, not decimal units like megabytes. So a 64GB unformatted card may show up as 59GB when formatted and accessible on a computer.

How long do Micro SD cards last?

With proper usage and storage, most Micro SD cards will last 3-5 years on average. Higher-end cards boasting more rewrite cycles and better NAND chips can last 5-10 years. Factors like manufacturing defects and physical damage also affect usable lifespan.

Why does my SD card keep disconnecting?

Frequent disconnects and connection issues most often stem from physical damage to the SD card’s pins or contacts, which interface with the device. Bent pins, corrosion, cracked solder joints, and other issues can interfere with the connection. Replacing the card is the best fix.

Can I use the same SD card in different devices?

It is generally fine to use the same SD card across different compatible devices like cameras, phones, and computers. However, regularly swapping the card between devices greatly raises the risk of corruption compared to using it for one device primarily. Some devices may also require reformatting the card first to be compatible.