Localhost Not Working After MacOS Sierra Upgrade I've tried other solutions I've found on StackExchange for this same problem, but must have a unique situation that is still causing problems. I have a hosts file setup as follows:

127.0.0.1               localhost.localdomain localhost     host.ciaciagi.com
255.255.255.255         broadcasthost
::1                     localhost.localdomain localhost     host.ciaciagi.com
fe80::1%lo0             localhost


I have httpd.conf setup and the line for LoadModule unique_id_module libexec/apache2/mod_unique_id.so commented out (as others have suggested).

I can ping 127.0.0.1 and get this:

$ ping 127.0.0.1
PING 127.0.0.1 (127.0.0.1): 56 data bytes
64 bytes from 127.0.0.1: icmp_seq=0 ttl=64 time=0.082 ms


I've run

$ sudo apachectl configtest
Syntax OK


I checked for a corrupt virtual hosts file. Everything was fine.

Restarting apache shows nothing significant (nothing at all):

$ sudo apachectl restart
$ 


Opening a browser and attempting to connect to http://localhost/ (I've tried 3 browsers and their private/incognito windows), I still get "Unable to connect" or its equivalent for the browser.

Any ideas?
People [including me] have had success by swapping 

::1    localhost

to

::1    127.0.0.1

though that's in a non-domain setup

worth a shot?