I ran into this after a power failure at my house. For some reason, it would not bind port 80 to my IPv6 address:
# /var/mdw/scripts/reverseproxy restart
:: Restarting reverseproxy
reverseproxy not running
:: Starting reverseproxy
[Thu Jun 01 12:35:00.997875 2017] [core:warn] [pid 3973:tid 1435722960] AH00111: Config variable ${URLHardening_HTTP_Hostname} is not defined
[Thu Jun 01 12:35:00.997986 2017] [core:warn] [pid 3973:tid 1435722960] AH00111: Config variable ${URLHardening_HTTP_Hostname} is not defined
[Thu Jun 01 12:35:01.000681 2017] [core:warn] [pid 3973:tid 1435722960] AH00111: Config variable ${URLHardening_HTTP_Hostname} is not defined
[Thu Jun 01 12:35:01.000718 2017] [core:warn] [pid 3973:tid 1435722960] AH00111: Config variable ${URLHardening_HTTP_Hostname} is not defined
AH00112: Warning: DocumentRoot [/var/www/REF_RevFroCcsweb01] does not exist
AH00112: Warning: DocumentRoot [/var/www/REF_RevFroCcsweb01] does not exist
(99)Cannot assign requested address: AH00072: make_sock: could not bind to address [2606:6000:5fc0:5:44bd:ad76:3adc:27bd]:80
no listening sockets available, shutting down
AH00015: Unable to open logs
I was able to work around this by disabling IPv6 temporarily, then restarting the reverseproxy service again.
Has anyone else seen this?