Troubleshooting & messages · Moves and copies that didn't finish
What does "The destination is read-only" mean?
Short answer: The drive can be read but not written — usually because it's formatted NTFS. Use an APFS or exFAT drive (reformatting erases it), or run First Aid in Disk Utility.
The drive you chose can be read but not written to, so nothing could be copied there. Your original is safe and untouched.
The usual cause is a drive formatted for Windows (NTFS), which macOS can only read. Less often, the drive's write-protect switch is on, or macOS mounted it read-only after finding a problem.
### What to do - Use a drive formatted as APFS (best for a Mac-only drive) or exFAT. - If the drive should be writable, run First Aid on it in Disk Utility. - Reformatting erases a drive — copy anything you need off it first.