‘Cannot read from the source file or disk’? Read this first

You are copying files off an external hard drive, a USB stick or a memory card and Windows stops with the message “Cannot read from the source file or disk.” Sometimes it happens on one file; sometimes the whole copy keeps stalling on file after file. A close relative is “Error 0x80070570: The file or directory is corrupted and unreadable.” These errors can have harmless causes, but they are also one of the most common early signs of a failing drive, so it is worth understanding them before you press “Try Again” for the twentieth time.

What the message actually means

Windows asked the source drive for a piece of data and did not get a usable answer. That can happen for two broad reasons:

• A problem with the file name or path. Windows cannot handle the file as named, so it never really tries to read the data.
• A problem reading the data itself. The drive tried and failed, because of bad sectors, a weak or damaged read head, worn flash memory or file system damage.

The pattern of the failures usually tells you which one you are dealing with.

Harmless causes worth ruling out

• Long paths. Files buried many folders deep can exceed the path length that some Windows programs handle. Try copying the parent folder to a short location such as D:\Rescue instead.
• Odd file names. Files created on a Mac, a camera or a Linux system can contain characters, trailing spaces or dots that Windows Explorer struggles with.
• Cable, port and power. A loose USB cable, a hub or a front-panel port can drop out mid-copy. Use a rear USB port directly on the computer, and a different cable if the drive has a detachable one.
• Another program holding the file. Antivirus scanning or a sync client can occasionally interfere; pausing them is a quick test.

If the error affects only a handful of files with long or unusual names, and everything else copies at normal speed, a name or path issue is the likely cause.

Signs it is the drive that is failing

• The copy gets slower and slower, then stops on certain files.
• Explorer freezes or shows “Not responding” when you open folders.
• The drive clicks, ticks, beeps or spins up and down repeatedly.
• It disconnects and reconnects with the Windows USB sound.
• The same files fail every time, and more files fail each attempt.
• A memory card or USB stick becomes very hot or briefly vanishes.

Any of these point to a physical problem. Hard drives with weakening heads or spreading bad sectors get worse with use, and flash drives with failing memory can stop responding altogether.

What not to do

• Do not keep clicking “Try Again”. Every retry forces the drive to read the same damaged area repeatedly, which is exactly the kind of work that can finish off a weak head.
• Do not run CHKDSK or “Scan and fix”. On a drive with read errors, CHKDSK can mark areas as bad and remove file records it cannot read, and on a failing drive the scan itself is a long, heavy workload.
• Do not format the drive, even if Windows later offers to.
• Do not leave a large copy running overnight on a drive that is clearly struggling.
• Do not open the drive’s case or swap its circuit board.

Safe next steps

1. If the drive seems healthy apart from a few named files, copy the most important folders first to a short path, one folder at a time.
2. If you see any of the warning signs above, stop and power the drive down. Get the files that matter most, if any are still copying normally, and then leave it alone.
3. Write down exactly what happened: the error text, which files failed, any noises, and whether the drive was dropped.
4. Get a professional assessment before trying recovery software, which reads the whole drive and puts it under the same stress.

In a lab, a failing drive is imaged with hardware that can read around bad areas, control retries and work head by head where necessary, so that the readable data is captured before the condition worsens. Files are then extracted from that copy, not from your original drive. We handle this every day for WD and other external hard drives, USB sticks and memory cards, and our Windows data recovery page explains more about file system damage.

Get advice before the drive gets worse

If Windows keeps telling you it cannot read from the source disk, stop the copy and call Data Retrieval on 020 7064 4996. We offer a free assessment with no obligation, and you can also request a quote online.