ERROR: epmd error for host localhost: nxdomain (non-existing domain) Start MQ and report an error

1. Error message

Start MQ, rabbitmq-server start

Error:

zhaohui@zhaohuideMacBook-Pro rabbitmq % rabbitmq-server start

BOOT FAILED
===========
ERROR: epmd error for host localhost: nxdomain (non-existing domain)

2023-08-10 09:19:51.202102+08:00 [error] <0.135.0>
2023-08-10 09:19:51.202102+08:00 [error] <0.135.0> BOOT FAILED
2023-08-10 09:19:51.202102+08:00 [error] <0.135.0> ===========
2023-08-10 09:19:51.202102+08:00 [error] <0.135.0> ERROR: epmd error for host localhost: nxdomain (non-existing domain)
2023-08-10 09:19:51.202102+08:00 [error] <0.135.0>
2023-08-10 09:19:52.220312+08:00 [error] <0.135.0>     supervisor: {local,rabbit_prelaunch_sup}
2023-08-10 09:19:52.220312+08:00 [error] <0.135.0>     errorContext: start_error
2023-08-10 09:19:52.220312+08:00 [error] <0.135.0>     reason: {epmd_error,"localhost",nxdomain}
2023-08-10 09:19:52.220312+08:00 [error] <0.135.0>     offender: [{pid,undefined},
2023-08-10 09:19:52.220312+08:00 [error] <0.135.0>                {id,prelaunch},
2023-08-10 09:19:52.220312+08:00 [error] <0.135.0>                {mfargs,{rabbit_prelaunch,run_prelaunch_first_phase,[]}},
2023-08-10 09:19:52.220312+08:00 [error] <0.135.0>                {restart_type,transient},
2023-08-10 09:19:52.220312+08:00 [error] <0.135.0>                {significant,false},
2023-08-10 09:19:52.220312+08:00 [error] <0.135.0>                {shutdown,5000},
2023-08-10 09:19:52.220312+08:00 [error] <0.135.0>                {child_type,worker}]
2023-08-10 09:19:52.220312+08:00 [error] <0.135.0>
2023-08-10 09:19:52.221082+08:00 [error] <0.133.0>   crasher:
2023-08-10 09:19:52.221082+08:00 [error] <0.133.0>     initial call: application_master:init/4
2023-08-10 09:19:52.221082+08:00 [error] <0.133.0>     pid: <0.133.0>
2023-08-10 09:19:52.221082+08:00 [error] <0.133.0>     registered_name: []
2023-08-10 09:19:52.221082+08:00 [error] <0.133.0>     exception exit: { {shutdown,
2023-08-10 09:19:52.221082+08:00 [error] <0.133.0>                          {failed_to_start_child,prelaunch,
2023-08-10 09:19:52.221082+08:00 [error] <0.133.0>                              {epmd_error,"localhost",nxdomain}}},
2023-08-10 09:19:52.221082+08:00 [error] <0.133.0>                      {rabbit_prelaunch_app,start,[normal,[]]}}
2023-08-10 09:19:52.221082+08:00 [error] <0.133.0>       in function  application_master:init/4 (application_master.erl, line 142)
2023-08-10 09:19:52.221082+08:00 [error] <0.133.0>     ancestors: [<0.132.0>]
2023-08-10 09:19:52.221082+08:00 [error] <0.133.0>     message_queue_len: 1
2023-08-10 09:19:52.221082+08:00 [error] <0.133.0>     messages: [{'EXIT',<0.134.0>,normal}]
2023-08-10 09:19:52.221082+08:00 [error] <0.133.0>     links: [<0.132.0>,<0.44.0>]
2023-08-10 09:19:52.221082+08:00 [error] <0.133.0>     dictionary: []
2023-08-10 09:19:52.221082+08:00 [error] <0.133.0>     trap_exit: true
2023-08-10 09:19:52.221082+08:00 [error] <0.133.0>     status: running
2023-08-10 09:19:52.221082+08:00 [error] <0.133.0>     heap_size: 376
2023-08-10 09:19:52.221082+08:00 [error] <0.133.0>     stack_size: 28
2023-08-10 09:19:52.221082+08:00 [error] <0.133.0>     reductions: 170
2023-08-10 09:19:52.221082+08:00 [error] <0.133.0>   neighbours:
2023-08-10 09:19:52.221082+08:00 [error] <0.133.0>
2023-08-10 09:19:52.241139+08:00 [notice] <0.44.0> Application rabbitmq_prelaunch exited with reason: { {shutdown,{failed_to_start_child,prelaunch,{epmd_error,"localhost",nxdomain}}},{rabbit_prelaunch_app,start,[normal,[]]}}
Kernel pid terminated (application_controller) ({application_start_failure,rabbitmq_prelaunch,{ {shutdown,{failed_to_start_child,prelaunch,{epmd_error,"localhost",nxdomain}}},{rabbit_prelaunch_app,start,[normal,[]]}}})

Crash dump is being written to: erl_crash.dump...done

2. Reasons and solutions

According to the error message, there is an error of epmd error for host localhost: nxdomain (non-existing domain). This error is generally caused by DNS resolution issues.

The solution is as follows:

1. Check if your host can successfully resolve the localhost domain name. It can be tested with the following command:

   ping localhost

2. If it cannot be resolved, there may be a problem with the DNS configuration. You can try modifying /etc/hoststhe file to localhostmap to the correct IP address, for example:

   127.0.0.1 localhost 
   ::1 localhost

3. Make sure your internet connection is working. Sometimes an unstable or disconnected network connection will cause DNS resolution to fail.

4. Check the RabbitMQ configuration file for errors. You can check rabbitmq.confthe configuration items in or other related configuration files to ensure that there are no wrong or illegal configurations.