Moving files from drive to drive or computer to computer is a common task in both office environments and on recreational PCs. Windows users that regularly transfer large files (particularly multi-gigabyte files) are no stranger to an error message that reads ‘can’t read from the source file or disk.’ This message can appear for three different reasons. The most common reason is a mismatch in the file systems on different drives or devices. Other common reasons for this error include corrupt disk sectors and file  permission problems. This article discusses how to resolve ‘can’t read from the source file or disk’ errors so that you can get your file transfers running smoothly.
The error most typically arises when moving a large file between two disks, whether between two internal drives or between an internal and external drive. The error can crop up on small files, but that is less common. It’s usually big files that cause the problem.
Fix #1: Mismatched file systems
Mismatched file systems are the most comfortable scenario to diagnose, but the hardest to fix as well. If you’re using Windows 8 or Windows 10, chances are your file system is NTFS. If you are using Windows 7, it could be FAT32 or NTFS.
NTFS is entirely different from FAT32 and can easily handle larger files. FAT32 is an older file system. If the disk you are transferring from is FAT32, the maximum file size it can handle is 4GB. If the file you are moving is even close to that size, it can cause issues.
- Select the hard drive with the file you are copying.
- Right-click the file and select properties.
- Identify the file system.
- Repeat for the destination disk.
If both file systems are NTFS, move on to Fix #2. If one disk is FAT32, read on.
Usually, you cannot copy large files onto FAT32 in the first place, but there have been instances where someone has used a file splitter to break a file into smaller pieces, and then the file became corrupted on the drive. Windows OS does not recognize that the file was broken down and just reads either a large or corrupt file.
If you see this, find a program that splits a file into smaller chunks and try the process again. You can Google ‘file splitter’ and find a wide variety of splitters, or you can just use GSplit , which is 100% free and full-featured application. Either way, install the program, split the file on the drive, move it as initially intended, and then rebuild it.
Fix #2: Bad sectors
A sector is a piece of storage. When formatting a hard drive, part of the process is dividing the hard disk drive (HDD) into individual sections to use independently to store data or to store larger files collectively.
Bad sectors are simply software errors that mean your computer cannot read the piece of data on that sector. They can be caused by actual physical damage, but that is less common.
To check for bad sectors:
- Select the hard drive you are trying to copy from.
- Right-click and select Properties, then the Tools tab.
- Select the Check button.
- Allow the process to complete.
- Repeat for the destination disk.
The disk checking tool is self-contained and will tell you if it finds bad sectors, and it will be able to repair them in the majority of cases. However, this process may damage the file you are trying to move. So, be aware of that before doing it.
You can also run disk checks from the command prompt if you prefer.
- Open a CMD window as an administrator.
- Type or paste ‘chkdsk /f D:’ and hit Enter. Change ‘D:’ to the hard drive letter in question.
- Let the process complete.
If there were bad sectors and they successfully got fixed, Windows may be able to move the file.
Fix #3: File permissions
Sometimes, Windows gets confused with file permissions  and has trouble letting go. It can also occur if you get sent a file by someone and Windows doesn’t give you ownership of that file. It can cause ‘can’t read from the source file or disk’ errors.
It is an easy one to fix though.
- Right-click the file you are trying to copy and select Properties.
- Select the Security tab and then click Edit in the center.
- Select the Add button in the center.
- Type your computer username in the box at the bottom and select Check Names.
- Select OK. This will take you back to the previous screen.
- Select your username in the top window, then check the box next to Full Control in the bottom box.
- Select Apply and then OK.
Windows should now allow you to move the file as you need without producing the ‘can’t read from the source file or disk’ error.