Being unable to copy a folder from a Mac to an external hard drive is a common issue that many users experience. This article will examine the various reasons why you may be unable to copy a folder from your Mac to an external drive and provide troubleshooting tips to resolve the problem.
We will cover factors like permission problems, drive format incompatibilities, insufficient space, corrupted files, connection issues, interference from third party apps, Apple’s optimized storage, and when you may need to seek further help. By the end, you should have a better understanding of why folder copying fails and how to fix it.
Permission Issues
One common reason you may not be able to copy a folder from your Mac to an external drive is due to permission errors. The Mac operating system uses permissions to control access to files and folders. This includes setting permissions on who can read, write, and execute files.
If the external drive you are trying to copy to has permissions set up to restrict writing files, you will get errors when trying to copy folders to it. For example, if the external drive is formatted as read-only or the permissions are set so your user account does not have write access. Some common permission errors when copying files are “Error code -36” or “The operation can’t be completed because you don’t have the necessary permission.”
To fix permission issues, you need to modify the permissions on the external drive. The easiest way is to erase the drive and reformat it, which will reset permissions. You can also use the Get Info window in Finder to view and change permissions on specific folders and files on the external drive. Lastly, if the drive is formatted for a Linux or Windows system, the permissions may be incompatible with macOS.
In summary, permission errors are a frequent reason for being unable to copy folders from a Mac to an external drive. Checking the drive permissions and reformatting if necessary can resolve these kind of issues.
Drive Format Incompatibilities
One common issue that can prevent copying folders from a Mac to an external drive is having incompatible drive formats between the two devices. Macs now use APFS (Apple File System) as the default format for internal drives, while external drives still often use HFS+ or exFAT.
APFS and HFS+ do not directly interact well together. As this Apple forum post explains, while you can copy individual files between APFS and HFS+ drives, copying entire folders may result in permissions errors or other issues. APFS has increased security protections that may cause problems when interacting with HFS+ formatted external drives.
Additionally, APFS and HFS+ are designed for Mac OS only. As discussed in this article on drive formats, they have limited functionality with Windows or other operating systems. On the other hand, exFAT can be read and written to by both Mac and Windows.
To avoid format incompatibility issues, consider reformatting your external drive to match your Mac’s internal drive format. Or use a universal format like exFAT if you need cross-OS compatibility. Checking that both the source and destination drives use the same file system format can help avoid folder copying errors.
Insufficient Space on Drive
One common reason you may be unable to copy a folder from your Mac to an external drive is if the external drive is full or nearly full. When a drive reaches capacity, macOS will prevent copying any additional files to prevent overwriting existing data. Before attempting to copy, check the external drive for available space.
To check the storage space on an external drive on Mac:
- Open Finder and select the external drive from the lefthand menu.
- In the Finder toolbar, click the Get Info button (letter i in a circle).
- In the Get Info window, look for Available space and note if there is less than 15-20% available.
If your external drive shows it’s nearly full, you’ll need to free up space before the copy can complete. Try deleting unused files or moving data to another device temporarily. After removing data, empty the Trash on the external drive.
You can also use Mac’s optimized storage features to clean up external drives. In System Preferences > Apple ID, enable Optimize Mac Storage which can automatically remove watched iTunes movies and TV shows on external drives. Additionally running the Reduce Clutter function in Storage Management can help identify rarely used files to delete.
With enough space freed up on the external drive, you should then be able to copy over a folder from your Mac. Check the drive info again afterward to confirm available space.
Corrupted Files
Corrupted files or folders can prevent copying from a Mac to an external drive. File corruption occurs when the data in a file becomes damaged, rendering the file unusable. This can happen for various reasons like a power outage, storage device issues, or abnormal system shutdowns. When you try to copy a corrupted file, the transfer will fail or result in more corrupted files.
To check for corrupted files, run a scan using Disk Utility. Go to Applications > Utilities > Disk Utility. Select your drive and click “First Aid” to scan and repair errors. Any files that can’t be fixed will need to be deleted. You can also try copying files from the terminal using the cp command with -f flag to force copy and skip errors. For example: cp -f /path/to/file /external_drive (1). This will copy any non-corrupted files and skip the damaged ones. Replacing damaged files from a backup is recommended.
Finally, if corruption is a recurring issue, it’s best to diagnose potential sources like faulty hardware, storage problems, or software bugs. Reformatting the external drive may also help resolve persistent corruption problems.
Drive Connection Issues
Sometimes an external hard drive is not detected on a Mac due to faulty cables, ports, or other connection problems that prevent proper communication between the drive and computer. This can prevent files and folders from being copied over.
Faulty or loose cables are a common culprit. Check that both ends of the USB, Thunderbolt, or other cable connecting the external drive to your Mac are fully plugged in. Try connecting the drive to another port on the Mac as well. Damaged or faulty cables can cause connectivity problems, so substitute cables if needed. Using higher quality cables certified for optimal data transfer rates can help too.
The ports themselves on either the external drive enclosure or Mac could also be damaged, dirty, or malfunctioning. Try connecting the drive to another computer to check if the drive’s ports are functioning properly. Clean any debris from the ports. For Macs, resetting the System Management Controller (SMC) can help troubleshoot port issues.
If the drive connects but keeps disconnecting during file transfers, the cable, ports, or enclosure electronics may be faulty. Contact the drive manufacturer for troubleshooting tips or replacement parts. Using a powered hub between the Mac and external drive may help stabilize power and connectivity.
Checking these drive connection components can help identify and resolve physical connectivity problems preventing file copying between a Mac and external hard drive. See https://discussions.apple.com/thread/254572440 for more troubleshooting tips.
Third Party Apps Interfering
Some third party apps like encryption or anti-virus software can interfere with copying folders and cause permissions issues. These types of apps may block copying as a security measure to prevent sensitive data from being duplicated or moved off your Mac without authorization.
To troubleshoot, check the settings of any anti-virus, encryption, or security software you have installed. There may be an option to allow or trust certain copy operations. Temporarily disabling certain features related to copying and permissions may also help identify if a third party app is the cause.
Additionally, some Mac optimization apps like CleanMyMac X have an “Uninstaller” feature that can completely remove leftover fragments from uninstalled apps. Using this to do a deep clean can wipe out any remnants of old apps that may still be blocking copy operations.
If the problem started after installing a new app, try uninstalling it and checking if folder copying works again. That can confirm whether the app is responsible.
Reference: https://discussions.apple.com/thread/734921
Apple’s Optimized Storage
One potential reason you may be unable to copy a folder from your Mac to an external drive is that Apple’s Optimized Storage feature has deleted the local copies of files to free up space on your Mac (https://support.apple.com/en-us/102624). When enabled, Optimized Storage uses iCloud to store full-resolution photos and videos while retaining lower-resolution versions on your Mac. This helps maximize the available storage space on your Mac.
If you try to access or copy a file that has been optimized for storage, you may find that the local copy no longer exists or has been replaced with a lower-resolution placeholder version. Attempting to copy this placeholder file to an external drive may result in an error or failed transfer.
To recover the full-resolution versions, you will need to disable Optimized Storage in your iCloud settings. This will download the original files from iCloud back onto your Mac, allowing you to fully access and copy them locally again. Just be aware this will take up storage space again. You can then re-enable Optimized Storage after copying the files to your external drive (https://discussions.apple.com/thread/251221348).
Restart and Try Again
If you still can’t copy the folder after trying the troubleshooting steps above, restarting your Mac and external drive may help. Here’s what to do:
- Safely eject the external drive.
- Shut down your Mac.
- Disconnect the external drive from your Mac.
- After 1 minute, reconnect the external drive and turn your Mac back on.
- Once fully booted up, try copying the folder again.
Restarting flushes out any software issues that may be preventing the copy. The fresh reboot ensures your Mac and external drive start up without any lingering processes interfering in the background.
After the restart, immediately try recopying the folder. If the folder copies over successfully now, then a simple restart was likely all that was needed to resolve the issue.
When to Seek Help
If you’ve tried all the troubleshooting steps and are still unable to copy folders from your Mac to an external drive, it’s time to seek professional assistance. Here are some guidelines on when to contact Apple support or a repair shop:
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You’ve restarted your Mac and reconnected the external drive multiple times but still get errors when copying folders.
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The external drive is not detected at all when plugged into your Mac.
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Your Mac frequently crashes or freezes when attempting to access the external drive.
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You’ve scanned for and removed any malware but the folder copy issue persists.
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The files you want to copy show up as corrupted on your Mac.
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You’ve reset NVRAM and SMC but the problem continues.
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You’ve tried copying the folders in Safe Mode but still have no luck.
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Your external drive is making unusual noises indicating a hardware problem.
In these cases, there may be a deeper underlying issue that requires a technician’s diagnosis and repair skills. Don’t continue troubleshooting endlessly on your own. Seek professional help to get your external drive and Mac working properly again.