Visual Studio Remote Debugger Firewall Error
An error occurred while launching remote debugging
It's a fairly common problem, in my experience.
The usual fix is making sure your network isn't blocking the remote debugger's port: 4024 for Visual Studio 2019, or 4022 for 2017.
That didn't work for me.
Solution
The web app had a custom domain, a subdomain set up as a CNAME in DNS.
I found the app's IP address (under Properties in Azure) and added
two entries to the Windows hosts file, one for the custom domain and one
for the original *.azurewebsites.net subdomain. That fixed
it.