The operation can't be completed: what Finder error codes -36, -43 and -50 mean
Copying to a USB drive or NAS stops with an error code and no explanation. What -36, -43 and -50 usually mean, and the fix to try first for each.
You drag a folder to a USB drive and Finder stops partway: The operation can't be completed because an unexpected error occurred, followed by a number. The number is the only clue Finder gives you, and it points to a different cause each time.
| Code | What it usually means | Try first |
|---|---|---|
| -36 | A read or write failed partway, often hidden ._ files or a failing drive | dot_clean, then First Aid |
| -43 | Finder could not find a file it expected | Download iCloud files, check the name |
| -50 | The destination refused the request | Rename the file, or check the drive's format |
Error -36
This is an input and output error. On drives formatted as ExFAT or FAT32 it is very often caused by the hidden ._ files a Mac writes beside each file. Clean them up, then copy again:
dot_clean -m /Volumes/YourDrive
dot_clean -m ~/path/to/the/folder/you/are/copyingMore on those files in dot underscore files. If the error keeps coming back on the same file, the drive may have a bad area. Run First Aid in Disk Utility, and copy with Terminal to see exactly which file fails:
cp -Rv ~/path/to/folder /Volumes/YourDrive/Error -43
Finder expected a file that was not there when it went to copy it. Common reasons:
- The file is in iCloud Drive and was not downloaded. Control-click, Download Now, then copy.
- The file was moved or renamed while the copy was running.
- The name has characters the destination does not accept, such as a colon or a trailing space on a Windows-formatted drive.
Error -50
The destination drive refused the request. This is common with drives formatted for Windows and with network shares. Rename files with unusual characters, check the file is not over 4 GB on a FAT32 drive (see file too large for the volume format), and try copying a smaller batch. If it happens on every file, reformatting the drive as ExFAT or APFS usually ends it, after copying anything on it somewhere else.
Copies that work but crawl are covered in copying files slow to an external drive.
Common questions
What does error code -36 mean on a Mac?
An input or output error during a copy. On ExFAT and FAT32 drives it is often caused by hidden ._ files, which dot_clean removes. If it keeps happening on the same file, check the drive with First Aid.
How do I fix error code -43 on a Mac?
Finder could not find a file it expected. Download iCloud files before copying, avoid renaming files during the copy, and remove unusual characters from file names.
What causes error code -50 when copying files?
The destination refused the request, often a Windows-formatted drive or a network share. Rename unusual file names, check the 4 GB FAT32 limit, or reformat the drive.