Fix 'This copy of the installer application is damaged' macOS Error

Updated at: 19/06/2025

Encountering the dreaded "This copy of the installer application is damaged" error on your macOS system? Don't panic! This frustrating message can often be resolved. This guide provides clear, step-by-step solutions to troubleshoot and fix this common macOS installation problem, getting you back on track quickly and efficiently. We'll cover various fixes, from simple checks to more advanced techniques. Let's get started!

Step-by-Step Instructions

  1. Find Release Date

    • Search for the release date of your macOS version on Google.
    Search for the release date of your macOS version on Google.
    Find Release Date

  2. Access Date & Time Settings

    • Open your Mac's Date & Time settings.
    • Unlock the Date & Time settings using your admin password.
    Unlock the Date & Time settings using your admin password. Unlock the Date & Time settings using your admin password.
    Access Date & Time Settings

  3. Adjust System Date

    • Uncheck 'Set date and time automatically'.
    • Manually set the date to just after the release date of your macOS version.
    Manually set the date to just after the release date of your macOS version. Manually set the date to just after the release date of your macOS version.
    Adjust System Date

  4. Run Installer

    • Run the macOS installer.
    Run the macOS installer.
    Run Installer
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Tips

  • For example, if installing macOS High Sierra (released September 25th, 2017), set the date to October 2017.

Common Mistakes to Avoid

1. Incomplete Download

Reason: The installer file may not have downloaded completely, leading to corruption.
Solution: Redownload the installer from the official source, ensuring the download completes without interruption.

2. Disk Space Issues

Reason: Insufficient free space on your hard drive can prevent the installer from running correctly.
Solution: Free up disk space by deleting unnecessary files or uninstalling unused applications before attempting to reinstall.

3. Damaged Download Source

Reason: The installer file may have been corrupted at its source (e.g., a broken link or server issue).
Solution: Try downloading the installer from an alternative source or contact the software provider for assistance.

FAQs

Why am I getting the 'This copy of the installer application is damaged' error?
This error usually means the installer file downloaded or copied is corrupted. This can happen due to a bad download, incomplete transfer, or disk errors. Sometimes, it's also caused by insufficient permissions or antivirus software interference.
I've tried everything, and the error persists. What should I do?
If basic troubleshooting steps (like restarting, checking disk permissions, or re-downloading the installer) fail, consider using Disk Utility to repair your disk. As a last resort, reinstalling macOS (from Recovery Mode) might be necessary. Always back up your data before attempting a reinstall.