Data Recovery Case File · Cameras, Drones & Cards · Stalled Is Better Than Finished
An Interrupted Format Wrote a Fifth of What It Intended and Stopped There
His enquiry reports an attempt that failed, and its failure is the fortunate part. A card a device suddenly declared unsupported, with the photographs no longer visible, where "I tried to format it but it just stays at twenty percent." A format that will not complete is a format that has not completed — and the fraction it reached bounds the damage precisely, which a finished one would not have done.
| Media | Memory card reported as unsupported by its host device — photographic content not visible; format operation initiated and stalling at approximately one fifth of its progress |
| Reported situation | Memory card in use as expansion storage · host device reporting the card as unsupported · photographic content no longer visible · format initiated by the owner · format progressing to approximately twenty percent · format not completing · photographs and videos sought |
| Fault class | Format interrupted by underlying read or write failure — writing bounded to the early portion of the address range; content beyond that region retained |
| Equipment used | Format progress treated as bounding the written region · no further formatting or repair permitted · card imaged write-blocked at genuine physical capacity · written region located and excluded from content reconstruction · content carved by signature beyond that region and validated by opening |
The decode: what the stall means, and why the unsupported message came first
What the message before all this reported: a volume the device could not interpret. Unsupported means the host read the card and did not recognise the structure describing its filesystem.
Why that alone would have been recoverable: the descriptor is small. A few hundred bytes determine recognition, and the photographs sit elsewhere on the card entirely.
Why the format was the natural response: the device offered it. A message about an unsupported card is usually accompanied by the only remedy the device knows.
What a format does when it runs: writes new structures. It creates a fresh empty filesystem and, depending on type, may write across the capacity.
Why stalling is therefore fortunate: it stopped writing. Whatever was written reached a fifth of the way and no further.
Why the stall itself is informative: something would not accept the write. A format halting at a consistent point has met a region the card cannot write or read reliably.
What that suggests about the underlying fault: degradation at a position. The card is failing somewhere around that point, which is likely what produced the unsupported message in the first place.
Why that makes the two symptoms one story: they share a cause. A region that cannot be read reliably explains both an unrecognised descriptor and a format that cannot pass it.
Why the content beyond that region is likely intact: nothing reached it. The format never got past a fifth, so four fifths of the card was never written to.
What must not happen now: no further format attempts. A retry would begin again from the start and might get further, which is the one thing that would make this worse.
On the bench
Format progress was treated as bounding the written region — an unsupported report meaning only that the host could not interpret the small descriptor identifying the filesystem, while a format writes new structures and, halting at a consistent point, indicates a region the card cannot reliably accept. That same region likely explains the original unrecognised descriptor. Four fifths of the card was never written to. The written region was located and excluded from reconstruction.
The outcome
Format progress treated as bounding the written region, further formatting refused, and content carved beyond that region. Free assessment, one fixed written figure including VAT; on cards where content has been deleted or overwritten, the figure is payable upfront. The decode: the format failing is the fortunate part. It stopped a fifth of the way, so four fifths of the card was never touched — and where it stalled is probably the same fault that started all this.
A format that will not complete
Don't retry it — a second attempt begins again from the start and might get further, which is the one thing that would make this worse. Read the stall as useful: a format halting at a consistent point has met a region the card can't reliably accept, which is probably the same fault that produced the unsupported message to begin with. And the fraction it reached bounds the damage, so most of the card was never written to at all.
Don't retry it — call Cambridge Data Recovery on 01223 655015; progress treated as bounding the written region, imaged at genuine capacity, content carved beyond the region the format reached.
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Our case files are drawn from genuine enquiries received by our laboratory over the past ten years, anonymised to protect client confidentiality. Each one describes the diagnostic and recovery procedure our engineers apply to that fault, using the equipment listed.