macOS External Drive Access Denied Error: Quick Fix

What Does the "Permission denied" Error Mean

The "Permission denied" message (or "Operation not permitted" / "Access denied" in Russian) appears when you try to copy files, create a folder, or edit a document on a connected external drive, but the operating system blocks the action. In macOS system logs, this is often accompanied by the EACCES (Error Access) or EPERM (Error Permission) error code.

The error occurs specifically at the moment of a write attempt. Reading files usually remains stable. The system checks the current user's permissions for the disk's mount point and denies access if the account isn't on the allowed list or if the file system doesn't support kernel-level write operations.

Common Causes

Access restrictions rarely occur without a reason. Most often, the issue stems from one of the following factors:

• NTFS file system. macOS can read NTFS data natively but cannot write to it. A connected drive is automatically mounted in read-only mode.
• Mismatched user identifiers (UID/GID). If the drive was previously used on another Mac or Linux system, permissions may be tied to a different user ID.
• Corrupted partition table or metadata. Abrupt cable disconnection or power loss can alter the root directory attributes on the volume.
• macOS security restrictions. Newer macOS versions (Ventura, Sonoma, Sequoia) enforce stricter access controls for external volumes. Occasionally, the Finder process temporarily lacks explicit permission to modify folder structures.

How to Fix It

Start with the first method. It is safe, requires no command-line work, and resolves the issue in most cases.

Method 1: Adjust Permissions via Finder

This method works if the drive is formatted with a supported file system (APFS, exFAT, FAT32), but permissions were reset after connecting to another device.

1. Open Finder and locate the external drive in the sidebar.
2. Select the drive and press Command + I (or right-click → Get Info).
3. At the bottom of the window, locate the Sharing & Permissions section. If it's collapsed, click the arrow to expand it.
4. Click the lock icon 🔒 in the bottom-right corner and enter your Mac administrator password.
5. Click the + button, add your user account, then select Read & Write from the Privileges column.
6. Close the window. The system will automatically apply the changes to the volume's root files.

💡 Tip: If the system displays "You don't have permission to make changes" after adding the user, the volume is mounted in read-only mode. Proceed to the next methods.

Method 2: Force Permissions via Terminal

When the graphical interface won't let you modify ACLs, use the command line. This method is fast but requires specifying the exact path.

1. Open the Terminal app (via Spotlight: Cmd + Space → Terminal).
2. Enter the following command to list the current volume names:

   ls /Volumes/
   

3. Locate your drive's name in the output. Replace DISK_NAME in the command below with that exact name (mind spaces and use quotes if necessary), then run it:

   sudo chmod -R 755 "/Volumes/DISK_NAME"
   

   This command recursively applies rwxr-xr-x permissions to all folders and files, granting read and execute access to everyone, and write access only to the owner.
4. To ensure ownership is transferred to the current user, run:

   sudo chown -R $(whoami) "/Volumes/DISK_NAME"
   

5. Enter your password (characters will not be displayed) and press Return.

⚠️ Warning: Never use the -R (recursive) flag on the root system partition /. Always double-check the /Volumes/... path to avoid breaking macOS.

Method 3: Repair the File System Using Disk Utility

If permissions won't change or the error persists across different ports, the directory structure or file system journal is likely corrupted.

1. Open Disk Utility (Applications → Utilities).
2. In the sidebar, select the external drive (the top-level device, not the partition underneath it).
3. Click the First Aid button in the top toolbar.
4. Confirm to start the process. The utility will scan the file system journal and automatically repair corrupted permission attributes.
5. Once finished, eject the drive, physically disconnect the cable, and reconnect it.

Prevention Tips

To prevent the "Permission denied" error from disrupting your workflow in the future, follow these best practices:

• Format drives correctly. For cross-platform compatibility between macOS and Windows, use the exFAT file system. It supports files larger than 4 GB and has no native write restrictions on macOS.
• Eject properly via Finder. Always use the Eject icon ⏏️ in the sidebar or press Cmd + E. Abruptly unplugging the cable can corrupt the permission journal.
• Keep NTFS drivers updated. If you absolutely need NTFS support, use trusted solutions like macFUSE + ntfs-3g or commercial drivers (Paragon, Tuxera). Update them alongside macOS releases to avoid conflicts with Kernel Extensions.
• Maintain backups. External drives are removable media. Keep important data in at least two separate locations to avoid dependency on file system stability or hardware failures.