The modcluster subsystem schema was updated to version 1.1 between 7.1.1 and 7.1.2. The new subsystem schema adds a new proxy-connector attribute which specifies the connector with which mod_cluster should communicate with httpd. The new attribute is required in version 1.1 of the schema, but for upgrade purposes defaults to "ajp". It seems you do not have a connector named "ajp" defined in your web subsystem. You probably want to either add an ajp connector, or set proxy-connector to "http".
Thanks that was very helpful. Yes I was able to set the connector to http and change the version of modcluster subsystem to 1.1 and get it to work.
There was one thing i noticed:
In the earlier versions, we have advertise=true by default, but if you specify proxy-list and it is non empty, then the subsystem uses the proxy list
In the current release, if i do not explicitly set advertise=false, the proxy-list is not used and it thinks we are still using multicasting, and fails when multicast socket binding are not specified.
So to get this running, i have set advertise=false and then it all works.