It's not just the installer. I ran nmap 7.70 from the command-line, and I received a warning saying nmap needed to be updated.

$ file `which nmap`
/usr/local/bin/nmap: Mach-O executable i386

Just to add to this - nmap won't run at all in macOS 10.15.
-bash: /usr/local/bin/nmap: Bad CPU type in executable

Can confirm this is an issue with the build in macOS 10.15.

Please update the binary to 64 bits.

I forgot to put it in the changelog, but I believe Nmap 7.80 was built for x86_64. Can someone on this thread confirm whether the new installer works? https://nmap.org/download.html#macosx

Hi, it doesn't work for macOS 10.15. New installs should be Notarised (verified/ signed) by Apple:

@vdeniet Thanks for checking. We are looking into Apple developer verification and tracking that as #94. If you are willing or able to change your preferences to allow installing unsigned packages, we would still like confirmation that this build executes on x64 macOS.

Hi, just confirmed it installs and executes fine on macOS 10.15. Thank you for updating it!

I can verify that nmap 7.80 shows as a 64-bit app on my macOS 10.14.

To install it on my macOS 10.14, after the alert that says it can't be opened, I had to go to System Preferences -> Security & Privacy -> General, and click the "Open Anyway" button, to be given the choice to open it. I am not sure if it is similar on macOS 10.15.

Hi, just confirmed it installs and executes fine on macOS 10.15. Thank you for updating it!

For me it also works now on 10.15

Great, thanks! I agree that code signing is an important step in macOS support, so we will definitely try to get that going. In the meantime, I'm closing this issue as resolved. Thanks!