What is Error -36?
Error -36 is an I/O error that shows up when you drag files to another folder, an external drive, or a network volume. You'll see a dialog that says something like: "The Finder can't complete the operation because some data in [filename] can't be read or written. (Error code -36)"
The most common trigger: you're copying a folder that contains a hidden file (like .DS_Store) or a file with a weird name, and the destination filesystem doesn't like it. It can also happen after a failed download or when a file is locked.
Good news: most of the time, this is fixable without wiping anything. Let's go step by step.
First, try the quick fix (30 seconds)
Use the Option key to force copy
- Instead of dragging the file, hold the Option key and drag it to the destination.
- If you're doing a move (cut/paste), try a copy instead. Select the item, press Command+C, go to the destination, press Option+Command+V.
What you should see: The copy starts, and the error might not appear. This works because it bypasses some Finder quirks. If it fails, move to the next step.
Moderate fix (5 minutes): Clear hidden .DS_Store files
Finder creates hidden files called .DS_Store in every folder to remember view settings. If one of those is corrupt, you get error -36.
- Open Terminal (find it in Applications > Utilities).
- Type this command and press Enter. It deletes all .DS_Store files in your home folder (you won't lose any data):
find ~ -name ".DS_Store" -delete - Now try copying the problematic file again.
What you should see: The copy proceeds without the error. If it still fails, the issue might be a locked or corrupted file.
Also, check file permissions. Select the file that's failing, press Command+I to get Info. At the bottom, look at Sharing & Permissions. If it says Read only for your user, click the lock icon, change it to Read & Write, then try copying.
Advanced fix (15+ minutes): Repair the disk or volume
If the error persists, it's likely a filesystem issue. This usually happens on external drives, but it can happen on your internal disk too.
Step 1: Run First Aid on the destination drive
- Open Disk Utility (in Applications > Utilities).
- In the left sidebar, select the drive you're copying to (not the source).
- Click First Aid and then Run.
What you should see: It may take a few minutes. When done, it'll say either "Operation successful" or list errors. If successful, try the copy again.
Step 2: Repair permissions (if you're on an older macOS)
If you're on macOS Catalina or earlier, you can use Terminal to repair permissions:
diskutil resetUserPermissions /This resets permissions for your user. On newer macOS (Big Sur and later), this doesn't do much; skip it.
Step 3: Check the source file for corruption
If the error names a specific file, that file might be corrupt. Try to open it. If it's a document, open it in its app and save a copy elsewhere. If it's a media file, play it in QuickTime — if it won't play, it's likely corrupt.
If you can't open it, you might need to recover it from Time Machine or accept the loss. That's rare, but it happens.
Step 4: Use a different copy method
Sometimes Finder is the problem, not the disk. Use Terminal to copy. This bypasses Finder's error handling:
cp -R /path/to/source /path/to/destinationReplace the paths with your actual ones. If Terminal reports an error, it gives a more detailed message like "Input/output error" or "Permission denied." That tells you exactly what's wrong.
What if nothing works?
You're likely dealing with a dying external drive. Check its SMART status (if it's a traditional HDD) using System Information (hold Option and click the Apple menu > System Information > Storage > select the drive). If it says Failing, back up everything you can immediately and replace the drive.
If it's a network volume, the server might be out of space or the connection is unstable. Try copying files in smaller batches.
One last trick: restart your Mac. A stale Finder process can cause this. I've seen that fix it more often than you'd think.
You don't need to try every step. Stop when the copy works.