Cause: bad sectors —
Data error (CRC) — why copying stops and how to save the files
If the device behaves unstably, it is also worth considering SSD/NVMe data recovery. For symptoms like these, the safest path is HDD data recovery instead of running more “live” tests.
You probably know the scenario: you connect an external drive and see your photos and documents. Good — they are still there. You select everything, click “Copy”, paste it to the desktop and wait. The progress bar reaches 5%, 30%, maybe even 99% and then suddenly stops. Red cross. Message: “Cannot copy the file. Data error (cyclic redundancy check)” (
Data Error – Cyclic Redundancy Check).
Windows stops the operation, and the file that was copied “halfway” disappears from the destination drive. Why does this happen, and can you force the computer to finish the job? If the drive has bad sectors or behaves unstably, professional HDD data recovery usually starts with sector-by-sector imaging.
What is CRC (Cyclic Redundancy Check)?
CRC is a mathematical “guard” of data integrity. Every file stored on a drive has a checksum. When you try to read it, the drive calculates that checksum again and checks whether it matches the original.
- If the checksum matches -> the file is copied.
- If the checksum does NOT match -> the drive knows the data is corrupted and sends a “CRC error” signal to the system.
In that situation, Windows tries to make sure you do not receive a damaged file and immediately stops the copy. It does not allow you to copy “whatever could be read”. For the system, a file is either 100% valid or it effectively does not exist.
Cause: bad sectors
— details
Most often, the reason is damaged sectors: the drive returns incorrect data or cannot read it, so the checksum (CRC) does not match and the copy ends with an error. Although a CRC error may suggest a cable issue, in 99% of cases it means physical damage to the disk surface exactly where that file is stored. It is like trying to read a sentence from a book where someone burned a hole through the page. You can see the beginning, you can see the end, but the middle is gone. The drive head tries to read that spot several times, and when it fails, it returns a CRC error.
⚠️ WARNING:
If the drive keeps grinding in one spot, makes strange noises and throws a CRC error —do not repeat attempts to copy the same file. Every such attempt forces the damaged head to work in the worst possible area, which can lead to total head failure and scratches across the rest of the platter.
Can tools like “Unstoppable Copier” help?
On the internet you will find programs that promise to “ignore CRC errors” and force the data through. Should you use them?
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In the case of photos:If the program copies a photo with a CRC error, you may see a grey stripe or a pixel shift in the damaged area. The photo may still be partially readable.
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In the case of archives (ZIP/RAR) and databases:even one bad bit can make the whole archive useless and impossible to unpack.
However, the main risk is not the file quality but the state of the drive. These programs hammer the disk with repeated attempts to read the damaged sector, which dramatically accelerates the degradation of the drive.
How are CRC errors bypassed professionally?
At Dysk i Spółka, we do not copy files with Windows Explorer. We use a method that protects your storage device:
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Binary copy (imaging):
We create an image of the entire drive, sector by sector, onto another healthy device.
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Damage mapping:Our equipment (PC-3000) reads the drive and, when it hits a CRC error, does not keep torturing it. It marks that sector as bad, skips it and continues reading the healthy data. We come back to the damaged areas only at the very end, using specialised read algorithms.
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Logical recovery:
Only after the image is created do we extract your files from that copy. That way we work on a safe duplicate and your damaged drive is no longer stressed.
Do you have a CRC error problem in Warsaw?
If the system refuses to copy key folders, do not fight it. Bring the drive to us. Very often only a few sectors are damaged, and we are still able to recover 99.9% of your data in perfect condition.
