Emergency · unstable SD card and reader
Read error while copying an SD card
What should I do when copying from an SD card fails with a read error?
Short answer
Do not keep retrying the copy: repeated file-by-file attempts stress the card and do not preserve its state. Swap once to a known-good reader and port. If the error recurs at the same position, create a sector image with a tool that logs bad areas, such as ddrescue, and recover from that image instead of repairing the card.
The situation
A copy stalls, disconnects, or reports unreadable data at a repeatable position.
A copy that fails at the same spot every time is telling you something about the medium, not about the file. Each retry asks the card to work harder at exactly the point where it is weakest, which is why the strategy has to change instead of the attempt.
01 / Diagnose
Work out what actually disappeared
The break can sit anywhere along the chain. Dirty or bent contacts, a cheap reader, a long cable or a passive hub produce errors that disappear with better hardware. A failing controller or worn flash cells produce errors that follow the card wherever it is plugged in, and those get worse with every read attempt.
The reader, contacts, controller, or flash cells may be unstable; repeated file-by-file retries do not preserve the card's state.
Check the last known path, trash and backups without writing to the original device.
02 / Protect the source
Preserve the best recovery chance
- 1
Stop the copy and change the hardware once: a different reader, a direct port instead of a hub, and a short cable.
- 2
Try a single copy on that setup and note whether the error appears at the same file and the same position.
- 3
If it does, stop copying files and image the whole card with a tool such as ddrescue that logs and skips unreadable areas.
- 4
Work only on the finished image from then on, scanning it read-only and exporting the files to a healthy drive.
Do not keep restarting the copy and do not run a repair or a surface test to force the bad area open. Repeated retries heat the card, can push a marginal controller into a permanent fault, and use up the few clean reads that remain.
03 / Choose the method
Match the tool to the source
For stable, readable exFAT, NTFS and FAT16/FAT32 or uncompressed IMG, DD, RAW and BIN images.
Unconfirmed exports are marked .UNVERIFIED.
Imaging preserves what the card still delivers and nothing more. File Recovery Hero can open an uncompressed IMG, DD, RAW or BIN image of an exFAT or FAT32 card on macOS and Windows, but sectors the reader never returned are simply not in it.
04 / Verify
Check the recovered content, not just its name
The imaging log is the report card: it names how many sectors were read and how many were skipped. Compare the image size with the card capacity, then open the exported files. A clip that stalls at a fixed timecode sits on top of one of the logged gaps.
Keep the source until two verified copies exist. One working preview is not enough.
Sources and technical references
FAQ
Questions about this recovery case
Can unstable SD card and reader be recovered in this situation?+
A copy that fails at the same spot every time is telling you something about the medium, not about the file. Each retry asks the card to work harder at exactly the point where it is weakest, which is why the strategy has to change instead of the attempt. The result still depends on what remains readable on the source.
What should I avoid before scanning?+
Do not keep restarting the copy and do not run a repair or a surface test to force the bad area open.
Does scanning write to my memory card?+
Your memory card is only read. Nothing is saved to it.
How do I know whether the result is complete?+
The imaging log is the report card: it names how many sectors were read and how many were skipped.