Quick Summary
Error code 16 on macOS typically indicates a problem with file permissions, disk space, or a corrupted installation file during a software update. This prevents the update process from completing successfully.
Common Causes
- Insufficient Disk Space: The update requires a certain amount of free space to download, expand, and install. If your hard drive is nearly full, the update may fail.
- File Permissions Issues: Incorrect file permissions can prevent the update process from writing necessary files to your system. This is a common cause, especially after transferring files between users or external drives.
- Corrupted Downloaded File: The update file itself may have been corrupted during the download process. This can happen due to network interruptions or other issues during the download.
- Interference from Third-Party Software: Security software or other third-party applications might interfere with the update process, especially if they restrict access or modify system files.
Step-by-Step Fixes
Method 1: Free Up Disk Space Show Steps ↓
Step 1: Check your available disk space by going to the Apple menu > About This Mac > Storage.
Step 2: Delete any unnecessary files, applications, or documents to free up at least 10-20 GB of space. Empty the Trash.
Step 3: Try the software update again by going to System Preferences > Software Update.
Method 2: Repair Disk Permissions with Disk Utility Show Steps ↓
Step 1: Open Disk Utility (Applications > Utilities).
Step 2: Select your startup disk in the sidebar.
Step 3: Click First Aid and then click Run. This will repair any disk errors and correct the file permissions.
Step 4: After the process is completed, restart your Mac and try the software update again.
Method 3: Download the Combo Updater Manually Show Steps ↓
Step 1: Go to the Apple Support Downloads website (search "Apple Support Downloads" on Google).
Step 2: Search for the combo updater for your version of macOS (e.g., "macOS Monterey 12.6 Combo Update"). Make sure you download the combo updater (not the delta update).
Step 3: Download the .dmg file. Once the download is complete, double-click the .dmg file to mount it.
Step 4: Run the installer package inside the .dmg. Follow the on-screen instructions to install the update.
Method 4: Disable Third-Party Security Software Show Steps ↓
Step 1: Temporarily disable any antivirus or security software installed on your Mac.
Step 2: Try the software update again by going to System Preferences > Software Update.
Step 3: If the update completes successfully, re-enable your security software. If the problem persists, check the security software's settings to see if it's blocking software updates and potentially configure it correctly.
Method 5: Boot into Safe Mode and Try the Update Show Steps ↓
Step 1: Shut down your Mac.
Step 2: Restart your Mac and immediately press and hold the Shift key until you see the Apple logo and the progress bar.
Step 3: Once logged in to Safe Mode, try the software update again by going to System Preferences > Software Update.
Step 4: If the update completes successfully in Safe Mode, restart your Mac normally. If this doesn't fix the issue, continue to the next step.