RabbitMQ_MQTT failing to start - rabbitmq

Question

I am trying to enable mqtt in rabbitmq. Plugin has been enabled successfully but when I make the changes in the config for rabbitmq_mqtt, it fails to start the service. Even after googling a lot, I am not able to see the same issue being raised.
RabbitMQ_MQTT is failing to load even when the port is available.
Starting broker...
BOOT FAILED
===========
Error description:
{could_not_start,rabbitmq_mqtt,
{{function_clause,
[{rabbit_networking,tcp_listener_addresses,
[{1993}],
[{file,"src/rabbit_networking.erl"},{line,176}]},
{rabbit_mqtt_sup,'-listener_specs/3-lc$^0/1-0-',3,
[{file,"src/rabbit_mqtt_sup.erl"},{line,55}]},
{rabbit_mqtt_sup,init,1,
[{file,"src/rabbit_mqtt_sup.erl"},{line,47}]},
{supervisor2,init,1,[{file,"src/supervisor2.erl"},{line,305}]},
{gen_server,init_it,2,[{file,"gen_server.erl"},{line,365}]},
{gen_server,init_it,6,[{file,"gen_server.erl"},{line,333}]},
{proc_lib,init_p_do_apply,3,[{file,"proc_lib.erl"},{line,247}]}]},
{rabbit_mqtt,start,[normal,[]]}}}
Log files (may contain more information):
/var/log/rabbitmq/rabbit.log
/var/log/rabbitmq/rabbit-sasl.log
{"init terminating in do_boot",{could_not_start,rabbitmq_mqtt,{{function_clause,[{rabbit_networking,tcp_listener_addresses,[{1993}],[{file,"src/rabbit_networking.erl"},{line,176}]},{rabbit_mqtt_sup,'-listener_specs/3-lc$^0/1-0-',3,[{file,"src/rabbit_mqtt_sup.erl"},{line,55}]},{rabbit_mqtt_sup,init,1,[{file,"src/rabbit_mqtt_sup.erl"},{line,47}]},{supervisor2,init,1,[{file,"src/supervisor2.erl"},{line,305}]},{gen_server,init_it,2,[{file,"gen_server.erl"},{line,365}]},{gen_server,init_it,6,[{file,"gen_server.erl"},{line,333}]},{proc_lib,init_p_do_apply,3,[{file,"proc_lib.erl"},{line,247}]}]},{rabbit_mqtt,start,[normal,[]]}}}}

Answer 1

You need to check the log in /var/log/rabbitmq/startup_log or /var/log/rabbitmq/startup_err. It is very possible that your changes for the config file is causing the problem. Usually, it's the syntax of the config file causing the problem. If you are using the classic format, it's array like syntax, having extra comma or missing comma could also prevent you from starting the service.