Finder error code -36 appears as: “The Finder can’t complete the operation because some data in ‘[item]’ can’t be read or written. (Error code -36).” Apple maps ioErr to -36. On current macOS releases, the message means a Finder copy, move, delete, restore, or transfer operation encountered a read/write failure. It does not identify which side failed. The safest first action is to stop repeated attempts, note the source and destination, and preserve any still-readable data before running a repair or considering an erase.
What Finder error code -36 means
The exact message can name a file, folder, or other item: “The Finder can’t complete the operation because some data in ‘[item]’ can’t be read or written. (Error code -36).” The item name and wording may vary, but the numeric signature remains -36.
The error can occur while Finder is copying, moving, deleting, restoring, or otherwise transferring an item on an internal disk, directly attached external or removable storage, or a mounted network volume. Apple’s documented mapping establishes the error identity, but it does not establish one universal cause.
Possible storage-related conditions documented in the supplied evidence include directory-structure or formatting errors, an unreadable item, a destination that cannot accept a write, an external device that is not maintaining a usable connection, or a disk that Disk Utility cannot repair. Do not assume hidden metadata files are the sole cause.
Data-preservation warning: If the disk may be failing, avoid repeated transfer or repair attempts. Back up as much readable data as possible before reformatting or taking another destructive action. Do not erase the disk as an early error -36 fix.
Identify the affected storage path before running a repair
Finder’s message reports that data could not be read or written, but it does not conclusively distinguish a source-side read failure from a destination-side write failure. Organize the investigation by recording the operation path rather than treating the named item as proof of which component failed.
| Record | Why it matters |
|---|---|
| Operation | Note whether Finder was copying, moving, deleting, restoring, or transferring the item. |
| Source | This is the location Finder needed to read during a copy, move, restore, or transfer. |
| Destination | This is the location Finder needed to write during a copy, move, restore, or transfer. |
| Named item | Record the file or folder shown in the dialog, without assuming it is the only affected component. |
| Failure pattern | Note whether one item failed or multiple items repeatedly fail while involving the same volume. |
If the source and destination are on different devices, both storage paths remain candidates until the available devices have been checked. For a delete operation, record the item’s current volume. For a restore operation, record both the restore source and its intended destination.
Classify the storage context
- Internal APFS storage: Use the Disk Utility First Aid sequence below. If the startup disk is involved, Apple’s procedure requires using macOS Recovery.
- External or removable storage that appears in Disk Utility: Preserve readable data and use First Aid on the relevant device hierarchy.
- External or removable storage missing from Disk Utility: Use the conditional connection procedure below before attempting First Aid.
- Mounted network storage: Treat it as a separate context. The approved evidence does not establish network-specific repair, SMB, authentication, or account procedures.
This classification narrows the affected path, but it does not conclusively prove whether Finder failed while reading the source or writing to the destination.
If an external drive is missing from Disk Utility, check its connection
When this applies: Use this procedure only when the affected storage is directly attached external or removable media and the device does not appear in Disk Utility. Do not apply this branch to an internal disk or turn it into a general missing-drive procedure.
Prerequisites: Confirm that the missing device is the external or removable storage involved in error -36. Preserve any readable data if the device becomes accessible.
- Shut down the Mac.
- Unplug non-essential devices.
- Reconnect the affected external device.
- Check its cable, physical connections, and power.
- Try again in Disk Utility.
Expected result: If the device becomes visible in Disk Utility, proceed to the documented First Aid sequence. If it remains unavailable, First Aid cannot be started on it from this workflow. Avoid improvised repairs and consider service or assistance from Apple or the storage-device provider, especially if important data is inaccessible.
Risk and rollback: This is a low-risk connection check with no intended data erasure. Reconnect the device normally if you need to undo the disconnected setup.
If the same device also disconnects, uses an unpowered hub, or triggers the separate USB Accessories Disabled warning, follow that warning’s dedicated power-related guidance. The USB warning and Finder error -36 are not equivalent errors.
Run Disk Utility First Aid in Apple’s documented order
When this applies: Use First Aid when the relevant internal, external, removable, or otherwise available storage appears in Disk Utility and error -36 suggests a storage problem. For mounted network storage, proceed only where the storage is actually exposed as a repairable device in Disk Utility; no separate network-specific procedure is confirmed here.
Prerequisites: Open Disk Utility and choose View > Show All Devices. Apple explains how to show all devices in Disk Utility. This view is necessary to see volumes, containers, and the storage device. If the startup disk is involved, use macOS Recovery; this article does not add unverified Recovery startup instructions.
If the disk may be physically failing, back up as much readable data as possible before continuing. First Aid is a non-destructive check, but Apple states that it cannot detect or repair every disk problem.
- Select a volume on the affected device and run First Aid.
- Repeat First Aid for every volume on that device.
- Select a container and run First Aid.
- Repeat First Aid for every container on the device.
- Select the storage device itself and run First Aid.
- If Disk Utility reports that the disk appears to be OK or was repaired, stop the First Aid sequence.
This order matters: volumes first, then containers, and finally the physical storage device. Running First Aid only once on the top-level device does not follow Apple’s Disk Utility First Aid instructions.
Expected result: Disk Utility may report that the selected storage appears OK or was repaired. That completes the documented check, but it does not guarantee that every file is readable or that Finder’s interrupted operation will succeed.
Risk and rollback: This is classified as low risk and does not require a rollback. Do not continue repeating First Aid if Disk Utility reports that the disk is about to fail or repeatedly says it cannot repair the problem.
What to do if First Aid fails or the disk is failing
When this applies: Use this escalation path only if Disk Utility says the disk is about to fail, cannot repair it, or First Aid fails repeatedly.
High data-loss risk: Reformatting erases the disk. Back up as much accessible data as possible before considering it. If Disk Utility says the disk is about to fail, stop repair attempts and prioritize preserving readable data.
Prerequisites: Some data must still be accessible for a new backup, and a separate backup destination must be available. If the data is inaccessible, this procedure cannot promise recovery.
- Back up as much readable data as possible to an available backup destination.
- If Disk Utility says the disk is about to fail, stop repair attempts.
- Reformat only after backup and only if you choose to assess the disk for reuse.
- Restore data after reformatting if a usable backup is available.
- Replace the disk or seek service if problems continue.
Expected result: A reformatted disk can be reassessed for use, but reformatting does not make a physically failing disk reliable and cannot recover data that was not backed up. Replacement or service may still be necessary.
Risk and rollback: This path is high risk because reformatting permanently erases the selected disk. The only documented rollback is restoring from an available backup. Verify the selected device and the backup before proceeding.
Limits for network volumes and unverified metadata fixes
The approved Apple evidence does not establish a network-volume-specific remedy for Finder error -36 beyond identifying the mounted storage context. If error -36 recurs only on a network volume, record the affected item, operation, source, and destination, then contact the storage owner or network administrator. Do not apply unverified SMB, account, authentication, or server procedures from this guide.
Some third-party instructions attribute every error -36 case to hidden .DS_Store or AppleDouble metadata and recommend metadata-cleanup commands. That cause is not established as universal by the approved evidence. No dot_clean syntax or metadata modification procedure is included because its exact case, effects, and risks require separate primary-source verification.
No material repair difference has been established for Apple silicon versus Intel Macs or among current macOS releases. The exact Finder wording and current Disk Utility interface should be manually verified before publication. This guide therefore stays limited to Apple’s error mapping, external-device connection branch, documented First Aid order, and failing-disk escalation.