Why do some files refuse to copy to an external drive?

The destination volume's format may not permit the file's size, name characters or metadata. Testing with a small, simply named file helps confirm this quickly.

Is a file error a sign of disk failure?

Not on its own. Repeated errors across unrelated files, unusually slow reads or unusual noises make hardware problems more plausible.

Should I repair the disk before copying my data off it?

Generally no. Copy important data to another location first where possible. Repair operations act on the volume that holds your files.

Why can I not empty the Trash?

Common reasons include an item still being used by an app, a locked item, or permissions on an external volume. These are usually resolvable without erasing anything.

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Mac Storage and Files: Finder, Trash, External Drives and Permissions

Storage and file help for the Mac — Finder behaviour, Trash errors, file permissions, external drives, disk formats and file transfer problems.

Updated July 16, 2026

Files are where most Mac error codes actually live. Copying, moving, renaming and deleting all involve a chain of assumptions — that the source is readable, the destination is writable, the name is legal on that volume, and the connection stays up for the duration.

This category covers Finder behaviour, Trash problems, permissions, external drives and disk formats, plus the file-transfer errors that follow when one of those assumptions fails.

Storage troubleshooting has an unusual property: the safest step is almost always to copy data elsewhere first. Repairs operate on the same volume that holds your files.

Common troubleshooting pathways

A copy fails partway through

Interrupted transfers point at connections, file names, volume formats or free space.

An item will not delete

Deletion failures usually involve permissions, locked items or files still in use.

Finder shows an unexpected error

Finder errors are a distinct family with their own likely causes.

An external drive keeps disconnecting

Cables, hubs, power and formats all affect stability.

Topic clusters

Finder

Unexpected Finder errors
Items that will not rename
Copy and move failures
Finder relaunch behaviour
Hidden and system items

Trash and deletion

Items in use
Locked files
Permission-denied messages
Emptying Trash safely
Items on external volumes

Drives and formats

Volume formats and their limits
File name restrictions
Large file transfers
Read-only volumes
Disk health signals

Getting started

1If a drive holds your only copy of something important, copy it elsewhere before troubleshooting the drive.
2Volume format explains many apparently random transfer failures, particularly with large files or unusual characters in names.
3A file that will not delete is usually in use by an app, not corrupted.
4Unmount drives properly. Repeated abrupt disconnection contributes to file-system inconsistencies.

Frequently asked questions

Mac Errors Backup & Recovery Mac macOS

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