What causes macOS Error 36?
Error 36 pops up when Finder tries to copy files to an external drive, network share, or even a USB stick. You'll see something like:
The Finder can’t complete that operation because some data in “filename” can’t be read or written (Error code -36).
Don't panic. The drive isn't dying. The file isn't corrupt. 99% of the time, it's a metadata problem — specifically, macOS's extended attributes or the dreaded .DS_Store files. These invisible files track folder view settings, and they can get weird when copying between different file systems (like NTFS or exFAT). I've seen this on everything from old MacBooks to the latest M2 Pro.
First fix: Kill the .DS_Store files (works 80% of the time)
Open Terminal (Finder → Applications → Utilities → Terminal) and navigate to the folder that's causing trouble. You'll want to clean out all those invisible files:
cd /path/to/your/folder
find . -name ".DS_Store" -delete
If that's too much to type, here's a simpler version that runs on the current folder:
find . -name "*.DS_Store" -type f -delete
After that, try copying the folder again. If it works, great. If not, move to the next step.
Why this works: Finder reads .DS_Store files to remember icon positions, view styles, and the like. When these files get truncated or contain invalid data — which happens all the time on network shares or drives formatted with non-Apple file systems — Finder throws error 36. Deleting them forces Finder to regenerate clean copies.
Second cause: Extended attributes (xattrs) messing with files
macOS stamps every file with metadata called extended attributes. Things like com.apple.quarantine (for downloaded files) or com.apple. Finder metadata. When these get out of sync, copying fails.
Check if a file has extended attributes:
xattr -l /path/to/file
If you see a bunch of com.apple.* entries, that's your culprit. Clear them all from a folder recursively:
xattr -cr /path/to/your/folder
The -c flag clears all xattrs, and -r runs it on every subfolder. This is my go-to when the .DS_Store trick doesn't cut it.
One real-world example: I had a client whose entire Photos library wouldn't copy to a Synology NAS. Every second file failed with error 36. Ran xattr -cr on the library folder and the copy completed in under five minutes. The photos themselves were fine — it was just that quarantine metadata from when they were originally downloaded.
Third cause: Finder caching glitch (more common than you think)
Sometimes Finder just holds onto a bad cache. It happens after a crash, a forced reboot, or when you've been copying a ton of files. The fix is trivial but surprisingly effective:
- Press Option + right-click on the Finder icon in the Dock and choose Relaunch.
- If that doesn't do it, restart your Mac. I know it sounds lazy, but a clean Finder state resolves error 36 in a decent number of cases.
Don't bother killing Finder from Activity Monitor — you'll just get a beach ball. Relaunching via the Dock is the clean way.
What if the file is already on the destination? Check permissions.
Less common, but if the destination folder has permission issues, copying can fail with error 36. Check the destination's permissions in Finder's Get Info panel. Make sure your user has Read & Write access. On a network share, this could be a server-side permission problem, so ask whoever administers the server.
For a quick test, copy the file to your Desktop first. If that works, the issue is the destination, not the file.
Quick-reference summary table
| Cause | Signs | Fix | Success Rate |
|---|---|---|---|
| Corrupt .DS_Store files | Error 36 on folders with many files | find . -name ".DS_Store" -delete | High |
| Extended attributes | Files downloaded from internet or emails | xattr -cr /path/to/folder | Very High |
| Finder cache glitch | Error appears randomly after heavy use | Relaunch Finder or restart Mac | Medium |
| Destination permissions | Copy fails only to a specific drive/folder | Fix permissions or check server side | Low, but check first |
In my experience, covering the first two causes will resolve error 36 for about 95% of people. The other 5% is either a genuinely failing drive or a network share that's misconfigured. Don't waste hours on it — run those Terminal commands, and you'll be back to copying files in minutes.