macOS Error 36 Fix: Copy Files Without Finder Failure

Error 36 means Finder can’t read or write a file, often after copying to external drives or iCloud. Here’s the quick fix and how to stop it coming back.

You’re not stupid—Error 36 is just cryptic

You try to drag a folder to your external SSD or iCloud Drive, and Finder slaps you with “The Finder can’t complete the operation because some data in ‘filename’ can’t be read or written. (Error 36)”. Infuriating, right? I’ve seen this on hundreds of Macs, from Mojave to Sequoia. The fix takes less than a minute.

The fast fix: purge those dot-underscore files

Open Terminal (it’s in Applications → Utilities). Type this, then hit Return:

dot_clean -m /Volumes/YourDriveName

Change YourDriveName to the actual name of the destination drive—no spaces issues if you quote it. Example:

dot_clean -m "/Volumes/My Passport"

After the command runs, you’ll see nothing. That’s normal—silence means success. Now try copying again. In 80% of cases, it just works.

What if dot_clean doesn’t find the drive?

List all mounted drives first:

ls /Volumes

You’ll see names like “Macintosh HD” and “Backup 1”. Use the exact name from that list.

Why this actually works

macOS stores extra metadata for every file you create using Apple apps or even apps like Adobe. That metadata lives in hidden files that start with ._ (called “AppleDouble” files). They travel alongside your real files when you copy to exFAT, FAT32, or some network drives that can’t store metadata natively. Windows and older Linux systems see these as random junk, but the real problem is when one of those ._ files gets corrupted—truncated to zero bytes, for example. Finder then tries to read that broken file, chokes, and gives you Error 36.

dot_clean -m scans the drive and merges any valid metadata back into the original files, then deletes those orphaned ._ files. No more bad data for Finder to trip over.

If dot_clean didn’t help—try these variations

1. The file itself is corrupted

In Finder, locate the file that caused the error. If you copied a folder, the error names a specific file. Check its size in Get Info (right-click). If it’s 0 bytes or ridiculously small, that file is toast. You might need to recreate it from the source. If the source is still intact, copy that single file using Terminal instead:

cp "/path/to/source/file" "/Volumes/Destination/file"

Terminal’s cp ignores those broken metadata files and copies the raw data. If that succeeds, your drive is fine.

2. Disk errors on the destination

Sometimes the drive has bad sectors. Run First Aid in Disk Utility. Click the drive name in the sidebar, hit First Aid, then Run. It takes a few minutes but can fix underlying issues that cause Error 36.

3. iCloud Drive version

If the error happens on iCloud, the problem is usually a stuck download or a file that iCloud hasn’t fully synced. Go to the iCloud folder in Finder, right-click the problem file, and select Download Now. If that option doesn’t appear, log out of iCloud (System Settings → your name) and back in. That refreshes the whole sync engine.

4. Focus on the source—Finder’s cache is weird

Rarely, Error 36 comes from a corrupted Finder cache. Log out and back in to your Mac user account, or restart. That clears the cached file handles that might be stuck. It’s a classic “have you tried turning it off and on again” but it genuinely works for this.

Stop Error 36 from coming back

Once you’ve cleaned your drive, think about how it got dirty in the first place. The #1 culprit is using Safari or Chrome to download files directly to an external drive. Those browsers write metadata files for every downloaded file, and a single interrupted download can leave a broken ._ file behind.

You can prevent that by:

Downloading to the desktop first, then moving the file to the external drive in Finder.
Formatting your external drive as APFS or Mac OS Extended (Journaled) if you never use it on Windows. Those formats store metadata natively, so ._ files don’t appear.
If you must use exFAT for cross-platform compatibility, run dot_clean on the drive every couple of weeks as routine maintenance. I have a reminder on my calendar.

Also, avoid yanking the drive out without ejecting. Unplugging mid-write is the fastest way to corrupt those metadata files. Click the eject icon next to the drive name in Finder, wait till it disappears, then pull the cable.

Pro tip: If you’re constantly copying between Windows and Mac, add dot_clean to your muscle memory. It’s a five-second fix that saves you an hour of googling every time.

That’s it. You’ll see Error 36 maybe once more in your life, and now you’ll know exactly what to do. Go copy your photos.