This is mandatory in 10.15: Notarizing Your Mac Software for macOS Catalina: As a reminder, Mac software distributed outside the Mac App Store must be notarized by Apple in order to run on macOS Catalina.
How on earth is this even legal?
gtk-osx-users: macOS 10.15.x and notarizing
More details in the original ticket: #2015
Another problem with Catalina: #2453.
See also Safely open apps on your Mac, and in particular: How to open an app that hasn’t been notarized or is from an unidentified developer
See Pythonmac-SIG: ctypes, codesigning, notarizing, py2app?: I’ve found a solution. Adding the following entitlement during codesigning allows me to use ctypes: com.apple.security.cs.disable-executable-page-protection
You can still run the app without having notarized: Can't you just right click?
this ticket has been moved to: https://github.com/Xpra-org/xpra/issues/2441