External drive read-only on your Mac?
Five causes, checked one by one
If an external drive is read-only on your Mac, the most common reason is that it uses Windows' NTFS format, which macOS can only read; after that come a write-protect switch, permissions, disk errors, and Windows Fast Startup. Press ⌘I to check the disk's format, then use the table below to find the cause in minutes.
External hard drivesPortable SSDUSB flash drivesSD cardLast updated
Find your cause in this table
Select the disk in Finder, press ⌘I to open Get Info, and check "Format" and "Sharing & Permissions" at the bottom.
| How to tell | How to fix | |
|---|---|---|
| The disk is NTFS (most common) | "Format" shows "Windows NT File System (NTFS)" | Install an NTFS read-write tool such as CrossDriver NTFS, or back up and reformat as exFAT |
| Write-protect switch on the SD card or reader | The small switch on the side of the SD card is slid to Lock | Slide the switch back and reinsert the card |
| Permission restrictions (APFS / Mac OS Extended) | Format is APFS or Mac OS Extended, and permissions say "You can only read" | Check "Ignore ownership on this volume" at the bottom of Get Info, or give yourself "Read & Write" access |
| The disk has errors | Disk Utility suggests running First Aid, or copying fails partway through | For NTFS, click "Repair Disk" in CrossDriver NTFS; for other formats, use First Aid in Disk Utility |
| Windows Fast Startup or hibernation | NTFS disk that CrossDriver reports as "not shut down cleanly" | Go back to Windows and hold Shift while clicking "Shut down," or repair the disk in the app before writing |
Getting "file too large" or "not enough space" when copying? See Can't copy files from a MacBook to a USB or external drive.
NTFS drives: enable writing with CrossDriver NTFS
No erasing, no restarting, and no changes to your Mac's security settings.
- 1
Download & install
Download CrossDriver NTFS from this site and drag it into the Applications folder.
- 2
Plug in your disk
The disk appears in the app's sidebar automatically. The free version opens it read-only in Finder so you can preview files and copy them to your Mac.
- 3
Turn on writing
Start a 7-day free Pro trial in the app or upgrade to Pro, and you can drag files onto the disk, delete, and rename in Finder.
- 4
Eject when you're done
Click "Eject" in the sidebar or in Finder, and wait for changes to be written to the disk before unplugging.
Q&A
Does "read-only" mean my drive is broken?
Usually not. The most common reason is that the disk is NTFS, which macOS can read but not write. If the same drive reads and writes fine on Windows, the drive is OK. Only repeated copy errors or strange noises point to a hardware problem—copy your important files off first.
Why can Windows write to my external drive but my Mac can't?
Windows uses the NTFS format, and macOS has built-in support only for reading it, not writing. Install CrossDriver NTFS to write in Finder. The free version is read-only; Pro comes with a 7-day free trial.
Can I fix it without installing software?
Yes, but you'll have to erase the disk: back up your files, then format the disk as exFAT in Disk Utility so both Mac and Windows can read and write it. See How to format an external drive on Mac for the steps. The widely shared trick of editing /etc/fstab usually no longer works on recent versions of macOS and can corrupt data, so we don't recommend it.
A USB stick is read-only on my Mac. How do I turn off read-only?
macOS has no single read-only switch, so fix the cause: if the USB stick or SD card adapter has a write-protect switch, slide it to unlocked; select the stick in Finder and press ⌘I, and if the format is NTFS, install an NTFS tool such as CrossDriver NTFS to write, or back it up and format it as exFAT; if it's APFS or Mac OS Extended and says “You can only read”, select “Ignore ownership on this volume” under Sharing & Permissions.
Does this happen with USB flash drives, SD cards, and portable SSDs too?
Yes, for the same reason—check the format. NTFS-formatted flash drives, SD cards, and portable SSDs are also read-only, and all of them become writable with CrossDriver NTFS. FAT32 and exFAT are already writable on a Mac.
Does this work on Macs with M1–M6 chips?
Yes. CrossDriver NTFS runs natively on Apple silicon and Intel Macs and supports macOS 12 Monterey, 13 Ventura, 14 Sonoma, 15 Sequoia, 26 Tahoe, and later—no kernel extension and no need to disable SIP.
Related products and guides
CrossDriver NTFS
Read and write NTFS external drives and USB flash drives on Mac, plus repair, format, and unlock BitLocker.
Mac can't write to an NTFS external drive
Mac can't write to an NTFS external drive: why, and three ways to fix it.
Can't copy files from a MacBook to a USB drive
Fixes for "file too large," "not enough space," and copy errors.
Format an external drive as exFAT or NTFS on Mac
Steps to format an external drive as exFAT or NTFS on a Mac.
Plug in your drive and try it free
Download CrossDriver NTFS and open your NTFS disk in Finder for free.
Download for Mac — Free preview