If you have administrative privileges on your computer, disable the antivirus, download the app, install the app and then re-enable the antivirus software. The antivirus software will quarantine and remove some key files that will prevent the app from launching and working properly. You may need to delete the app and all its associated files and reinstall it. You can skip to STEP 2 if you've tried downloading and installing and are still getting the error.
Open the AVG program.
Open menu Options.
Select Virus Vault.
Select the file that you wish to restore.
If needed, click Details to display more information about the removed infection.
You're then going to copy this file and create an exception:
Open the AVG user interface and go to Menu ▸ Settings.
Ensure General is selected in the left panel, then click Exceptions ▸ Add Exception.
Add an exception in one of the following ways: Type the file path, folder path, URL, or command prompt line into the text box, then click Add Exception. (You're going to paste the file you copied from the vault here)
Right-click on the Avast tray icon
select Virus Chest
Find the quarantined file
You will need to restore it, and copy it, and then create an exception.
-Add an Exception:
Open the Avast Antivirus user interface and select ☰ Menu ▸ Settings
Ensure the General tab is selected
then click Exceptions
Click the Add Exception button
Add an exception in one of the following ways: Type the file path, folder path, or URL into the text box, then click Add Exception. (you will paste the file you copied earlier into the box here)
To fix this, you will need to uninstall the app, and then reinstall it in the applications folder. See Can I install the app on a different drive? for more information.