In a post on the Apple Developer site, the tech giant notes that, starting February 3, 2020, all submitted software for macOS must be notarized by Apple in order to run by default on macOS Catalina. 

In September, the company temporarily adjusted the notarization prerequisites, saying it wanted to make this transition easier and to protect users on macOS Catalina who continue to use older versions of software. 

“If you haven’t yet done so, upload your software to the notary service and review the developer log for warnings,” Apple says. “These warnings will become errors starting February 3 and must be fixed in order to have your software notarized. Software notarized before February 3 will continue to run by default on macOS Catalina. As a reminder, all installer packages must be signed since they may contain executable code. Disk images do not need to be signed, although signing them can help your users verify their contents.”