The new Catalina OSX and Big Sure have a more restrictive “Gatekeeper” than before. To fix this, go into System Preferences > Security & Privacy > General. Make sure that under “Allow apps downloaded from” that it is set to “App store and identified developers.”

Even after turning on the setting above, “Gatekeeper” will likely block opening the app. If so, go into Security & Privacy and you will see an additional message asking whether you want to open the blocked app anyway. Proceed to approve.

For more information, read the article, “Safely open apps on your Mac,” at and/or search for keywords Catalina / override / Gatekeeper on Google or another search engine.

We’ve also heard that if you aren’t able to open the installer, you can right click it and choose “open with installer”.

Hope this helps and thanks for using DNAGedcom.