When you install the latest version of Norton, you need to configure the Security & Privacy settings to allow Norton System Extensions. If you did not complete these steps, you see this error message and a prompt to complete the configuration to finish the setup.

To fix this problem, depending on your operating system, select one of the following:

I have macOS X Catalina (10.15.x) or later

1. In the Norton alert window, click Finish Setup.
2. In the Norton installation window that appears, click Open Preferences.

   If you already have Norton installed and installing an update, in the Update Completed window, click OK and skip to step 7.

3. If you see the System Extension Blocked alert, click Open Security Preferences.
4. In the Security & Privacy window, click the lock icon at the bottom.
5. When prompted, type your administrator account password, and then click Unlock.
6. Click Allow corresponding to the Norton message, navigate back to the Norton installation window, and then click Continue.

   

   If you do not see the Allow button, then close and reopen the Security & Privacy window to view the Allow button.

7. In the Norton installation window, click Continue, and then click Allow to allow Norton to monitor all the network activities and block malicious website from accessing your Mac.
8. In the Norton installation window, click Open Preferences to allow Norton to access your disk for better protection.
9. In the Security & Privacy window, ensure that the Norton System Extension option is enabled. Navigate back to the Norton installation window and click Complete.

I have macOS High Sierra (10.13.x) to macOS Mojave (10.14.x)

1. In the Norton main window, under the “You are at risk” prompt, click Open Now or Click here.
2. In the Security & Privacy window, next to the message about Norton software being blocked, click Allow. If the Allow option is grayed out, click the lock icon in the left-bottom corner of the window, and type your administrator password to authenticate.

   If you do not see the Allow button, then close and reopen the Security & Privacy window to view the Allow button.

3. In the Norton Security installation window. click Continue.
4. Click Restart to complete the installation process.

Source : Official Norton Brand
Editor by : BEST Antivirus KBS Team