Никто, кроме Вас. А вот когда Вы посмотрите логи, напишите, что там за ошибки, то, может, кто-то и подскажет.
Высылаю лог-файл: /var⁄log⁄cups/error_log
E [21/Dec/2017:11:25:39 +0300] Unable to bind socket for address 127.0.0.1:631 - Address already in use.
E [21/Dec/2017:13:43:01 +0300] Unable to bind socket for address 127.0.0.1:631 - Address already in use.
E [22/Dec/2017:09:43:35 +0300] Unable to bind socket for address 127.0.0.1:631 - Address already in use.
E [22/Dec/2017:12:48:07 +0300] Unable to bind socket for address 127.0.0.1:631 - Address already in use.
E [22/Dec/2017:13:34:19 +0300] Unable to bind socket for address 127.0.0.1:631 - Address already in use.
E [25/Dec/2017:10:32:06 +0300] Unable to bind socket for address 127.0.0.1:631 - Address already in use.
E [25/Dec/2017:11:28:56 +0300] Unable to bind socket for address 127.0.0.1:631 - Address already in use.
E [25/Dec/2017:12:47:10 +0300] Unable to bind socket for address 127.0.0.1:631 - Address already in use.
E [26/Dec/2017:08:10:38 +0300] Unable to bind socket for address 127.0.0.1:631 - Address already in use.