Introduction

If you’re using Docker on macOS and encountering the error message "‘Docker.app’ will damage your computer," it can be frustrating and confusing. This issue typically occurs when macOS detects a problem with the app’s integrity or source. Fortunately, there are several steps you can take to resolve this issue and successfully run Docker on your Mac. 

In this guide, we'll go through some methods to fix this error and get Docker running smoothly.

Steps to Resolve the Warning

1. Allow Docker Through Security Preferences

The first thing to check is macOS's Gatekeeper security feature, which might be blocking Docker from running due to its source or integrity. Here’s how to allow Docker to run:

1. Open System Preferences:

• Go to Apple Menu > System Preferences > Security & Privacy.

2. Allow Docker to Open:

• In the General tab, look for a message at the bottom that says “‘Docker.app’ was blocked from use because it is not from an identified developer” (or something similar).
• Click Allow Anyway next to this message.

3. Try Opening Docker Again:

• After clicking "Allow Anyway," try opening Docker again. This should bypass Gatekeeper and allow the app to launch.

2. Reinstall Docker

Sometimes the issue may be related to a corrupted Docker installation. To fix this, reinstall Docker from a trusted source:

1. Uninstall Docker:

• Drag the Docker.app from the Applications folder to the Trash.
• Optionally, clear any residual Docker files from ~/Library/Containers and ~/Library/Application Support to ensure a clean uninstallation.

2. Download Docker from the Official Website:

• Go to the Docker website and download the latest version of Docker for macOS.
• Ensure you download Docker from the official Docker site or the Mac App Store to avoid potentially unsafe versions.

3. Install Docker:

• Double-click the downloaded .dmg file and follow the installation instructions.
• Once installed, try opening Docker again.

3. Use the spctl Command to Bypass Gatekeeper

If the error persists, you can manually allow Docker to run by using macOS's spctl (security policy control) command:

1. Open Terminal:

• Go to Applications > Utilities > Terminal.

2. Run the Command:

• In the Terminal, type the following command to disable Gatekeeper for Docker:

  sudo spctl --master-disable

3. Try Opening Docker Again:

• After running the command, try launching Docker again. This should disable Gatekeeper and allow Docker to run without security checks.

4. Re-enable Gatekeeper (Optional):

• If you want to re-enable Gatekeeper after running Docker, you can do so with the following command:

  sudo spctl --master-enable

4. Check for System Integrity Issues

If none of the above steps work, it’s possible that macOS’s system integrity has been compromised or there’s a deeper issue:

1. Run Disk Utility:

• Open Disk Utility (found in Applications > Utilities).
• Select your startup disk and click First Aid to repair the disk.

2. Update macOS:

• Make sure your macOS is up to date by going to System Preferences > Software Update. An outdated system may cause compatibility issues with apps like Docker.

3. Check Permissions:

• You can also check your file and app permissions to ensure that Docker has the correct access. Sometimes the app might be restricted due to incorrect file permissions.

Conclusion

If you're receiving the error "'Docker.app' will damage your computer" on macOS, the issue is often related to Gatekeeper or a corrupted installation. 

By adjusting your security preferences, reinstalling Docker from an official source, or using the spctl command to bypass Gatekeeper, you can resolve the issue. If these steps don't solve the problem, check for system integrity issues, update macOS, and verify that Docker is properly installed.