After upgrading to MacOS Catalina, I could no longer connect to open WiFI networks, specifically hotel networks and coffee shops. Previously, when connecting to one of these networks, a dialog would appear to ask for confirmation, a username/password combination, etc. No longer with Catalina.
After some extensive searching on the internet, the solution I found is launching the
Captive Network Assistant manually. I wrote a small bash script to launch it from the command line on a terminal window:
#!/bin/bash /System/Library/CoreServices/Captive\ Network\ Assistant.app/Contents/MacOs/Captive\ Network\ Assistant
(You should always use some kind of VPN when connecting to non-encrypted public networks.)