Quick Summary
Error 43 on macOS typically indicates that the file you are trying to access is currently in use by another application or process. This prevents you from modifying, moving, or deleting the file until it is released.
Common Causes
- File is actively open in an application: The most common cause is that an application currently has the file open. This could be a word processor, image editor, or any other program that directly interacts with the file.
- Background process using the file: A background process or service might be accessing the file. This could be an indexing service, backup software, or a syncing application.
- File system errors: In rare cases, file system corruption can cause a file to appear to be in use when it is not. This requires more advanced troubleshooting.
- Conflicting Permissions: Incorrect file permissions may lead macOS to believe a file is in use, even when it is not actively open.
Step-by-Step Fixes
Method 1: Close the Application
Step 1: Identify which application is using the file. Often, the error message will provide a clue, but if not, consider which applications were recently used to access or edit the file.
Step 2: Fully quit the application. Make sure it's not just minimized but completely closed. You can do this by right-clicking the application icon in the Dock and selecting 'Quit'.
Step 3: Attempt to access the file again to see if the error persists.
Method 2: Check for Background Processes using Activity Monitor
Step 1: Open Activity Monitor (Applications > Utilities > Activity Monitor).
Step 2: Search for processes that might be using the file's name or related applications.
Step 3: If you find a suspicious process, select it and click the 'X' button in the toolbar to forcefully quit it (use with caution, as this may cause data loss in the interrupted process). Confirm in the prompt if you are sure.
Step 4: Try accessing the file again.
Method 3: Restart your Mac
Step 1: Save any unsaved work.
Step 2: Restart your Mac by going to the Apple menu and selecting 'Restart'.
Step 3: Once your Mac restarts, try accessing the file again. Restarting closes all processes and releases file locks.
Method 4: Repair Disk Permissions (Disk Utility)
Step 1: Open Disk Utility (Applications > Utilities > Disk Utility).
Step 2: Select your startup disk in the sidebar.
Step 3: Click 'First Aid' and then 'Run' to repair disk permissions. This can sometimes resolve issues where file ownership or permissions are incorrect.
Step 4: After the process completes, try accessing the file again.
Method 5: Safe Boot
Step 1: Shut down your Mac.
Step 2: Press the power button to start your Mac. Immediately press and hold the Shift key until you see the Apple logo. This will boot your Mac in Safe Mode.
Step 3: In Safe Mode, try accessing the file. Safe Mode prevents certain software from loading, which can help determine if third-party software is causing the issue.
Step 4: Restart your Mac normally to exit Safe Mode.