Can’t read from the source file or disk

​You plug in your external hard drive, USB stick, or SD card, and try to copy or move a file only to be met with the dreaded message: “Can’t read from the source file or disk.” Suddenly, your seemingly simple objective perhaps backing up crucial files, accessing vacation photos, or transferring work documents grinds to a halt. You find yourself locked out, staring at a vague error message that offers no clear direction or solution.

This error, while common, can be deeply disruptive. It raises immediate concerns: Is the file corrupted? Is the disk failing? Will I lose all my data? For casual users, this can induce panic. For professionals, it can mean missed deadlines and disrupted workflows.

But don’t worry this problem is usually solvable. It’s typically caused by issues related to file corruption, hardware problems, file system incompatibility, or permission restrictions. Understanding these causes and learning how to troubleshoot them step-by-step can save you time, stress, and even data.

Let’s get started with the root causes before moving on to the most effective fixes.

Section 1: Error 

The error message “Can’t read from the source file or disk” typically appears in Windows when you’re trying to copy, move, or delete a file. It may also appear while syncing files, opening large files, or accessing data on external media.

1.1 What This Error Really Means

“Source File” refers to the file or folder you’re trying to access or move.

“Disk” refers to the storage media (hard drive, SSD, USB stick, SD card, etc.) where that file resides.

The system is basically telling you: “I tried to access this file from your storage device, but something went wrong, and I couldn’t complete the operation.”

1.2 Common Scenarios Where This Occurs

Transferring files between external drives and PCs.

Accessing old files on backup devices.

Moving files from NTFS to FAT32 systems (file system compatibility issues).

Corrupted or partially downloaded files.

Interruptions during file transfers.

1.3 Devices Typically Affected

External hard drives.

USB flash drives.

Memory cards.

Optical discs (CDs/DVDs).

Network drives.

Section 2: Root Causes Behind the Error (Approx. 500 Words)

Understanding the possible causes behind this error is critical to solving it. Here are the most common culprits:

2.1 File System Corruption

When the file system gets corrupted—due to unsafe removal of drives, power outages, or software bugs—the OS may no longer be able to read files correctly, triggering this error.

2.2 Bad Sectors on the Disk

Hard drives and USB sticks develop bad sectors over time. If your file resides in one of these, Windows will fail to read from it.

2.3 File Size Limitations

Trying to copy a file larger than 4GB onto a FAT32 drive? That will definitely cause an error, though Windows might not tell you explicitly. It may simply say it can’t read the file or disk.

2.4 File Permissions or Ownership

Files moved from one PC to another may retain user permissions that block access. If your account doesn’t have the right access, the system might deny the read operation.

2.5 Hardware Connection Issues

Loose USB cables, damaged ports, or defective drives can all disrupt communication between the OS and the storage device.

2.6 File Name or Path Issues

Windows has a 260-character path limit. If the file name or directory tree is too long, you may encounter this error.

2.7 Antivirus/Firewall Interference

Security software may block certain operations if it suspects a file is dangerous or compromised.

Section 3: How to Fix “Can’t Read from the Source File or Disk” (Approx. 1.200 Words)

Let’s walk through a variety of methods you can use to fix this problem. Try them in order—from the easiest and most likely to work, to the more technical ones.

3.1 Restart Your Computer

Simple but effective. A restart can resolve temporary glitches affecting file read/write operations.

3.2 Reconnect the Storage Device

Disconnect the external drive, USB, or SD card.

Wait 10 seconds.

Reinsert it and let the system remount it.

Try a different port or cable if the problem persists.

3.3 Copy to Another Location

Try copying the file to a different folder or even a different storage device. This can isolate whether the problem lies with the source file, the disk, or the destination.

3.4 Rename the File or Shorten the Path

Windows can’t read files with long directory paths. Try this:

Move the file to the root directory (e.g., C:\).

Rename the file with a simple name, like file.txt.

3.5 Check File Size and Drive Format

If you’re copying to a USB or SD card:

Right-click the drive → Properties.

If it’s FAT32 and your file is over 4GB, you’ll need to reformat the drive to exFAT or NTFS.

Back up the drive first reformatting erases all data.

3.6 Run CHKDSK to Check for Disk Errors

Corrupted file systems or bad sectors? Use CHKDSK.

Open Command Prompt as Admin.

Type:

bash

CopyEdit

chkdsk X: /f /r

Replace X: with your drive letter.

Press Enter. It may take a while if the drive is large or heavily used.

3.7 Check Disk Health with CrystalDiskInfo or SMART Tools

A failing hard drive often causes read errors. Use tools like CrystalDiskInfo to assess disk health (look for “Caution” or “Bad” status).

3.8 Disable Antivirus Temporarily

Some antivirus programs falsely flag files as malicious and block them from being read. Try:

Disabling real-time protection temporarily.

Attempting to access the file again.

Turn it back on after testing.

3.9 Use File Unlockers or Recovery Software

If the file is locked or partially corrupted:

Try Unlocker, LockHunter, or IObit Unlocker to unlock it.

Use Recuva, PhotoRec, or Panda Data Recovery to extract inaccessible files.

3.10 Take Ownership of the File

Right-click the file → Properties.

Go to Security tab → Advanced.

Click Change next to Owner.

Type your username and click OK.

Apply changes.

Now try accessing or moving the file.

3.11 Try Accessing the File in Safe Mode

Boot your PC in Safe Mode and attempt to copy/move the file. Some background processes and drivers are disabled in Safe Mode, reducing conflicts.

3.12 Try a Linux Live USB

Linux is more forgiving with file system errors and may access the file successfully.

Create a Linux Live USB (Ubuntu or Mint).

Boot from it.

Mount your drive and attempt the transfer.

3.13 Recover the File Using Data Recovery Tools

If the file is corrupted or partially deleted:

PhotoRec: Open-source, powerful, good for file fragments.

EaseUS Data Recovery: User-friendly, good for Windows users.

R-Studio: Professional-grade recovery for advanced users.

3.14 Replace or Repair the Hardware

If none of the above work, your storage media may be physically failing.

Test it on another PC.

If the issue persists, back up what you can and replace the drive.

Section 4: How to Prevent This Issue (Approx. 300 Words)

Avoiding this error in the future is possible if you follow good digital hygiene:

4.1 Safely Remove Drives

Always use the “Eject” feature before unplugging USBs or external hard drives.

4.2 Backup Regularly

Keep backups of critical files on multiple devices and cloud storage (like Google Drive or Dropbox).

4.3 Use Reliable Storage Media

Cheap USBs or no-name hard drives are prone to failure. Invest in trusted brands like SanDisk, Samsung, WD, or Seagate.

4.4 Monitor Drive Health

Use CrystalDiskInfo or Hard Disk Sentinel to keep an eye on SMART stats and temperature.

4.5 Avoid Long File Names/Paths

Keep directory structures simple and filenames short to reduce errors from Windows path length limitations.

4.6 Update Drivers and Windows

Outdated drivers and systems may misbehave. Ensure your OS and storage controller drivers are up to date.

Encountering the “Can’t read from the source file or disk” error can be deeply frustrating—especially when it happens at a critical moment. However, as this guide has shown, most causes are rooted in fixable issues: file system corruption, bad sectors, incompatible file formats, or even just overly long file names. The key is to stay calm, methodically isolate the cause, and apply the appropriate fix.

With powerful built-in tools like CHKDSK, external software like Recuva or PhotoRec, and even bootable Linux environments, modern users have a full toolbox at their disposal. The important thing is not to panic or take rash actions like formatting a drive before exhausting recovery options.

And most importantly, let this serve as a wake-up call to prioritize data integrity going forward. Make regular backups, safely remove drives, and invest in reliable storage media. That way, even if a file becomes unreadable or a drive begins to fail, you’ll never be more than a few clicks away from a solution—or a backup.

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