rabbitmq failed to start

[dipualnur]

Describe the bug

Hello rabbitmq community,
I am currently facing this error code, as I updated my system ( sudo apt update && sudo apt upgrade) , I tried to diagnosis the error, but as I am not from computer science background didn't understand much.

I am pasting below the output, I am using Linux Ubuntu 22.04 LTS and RAM is 16GB with I311thGen<
Hope, these info can be helpful to clariy.

sudo rabbitmq-diagnostics -q status

Error: unable to perform an operation on node 'rabbit@mdmonirul'. Please see diagnostics information and suggestions below.

Most common reasons for this are:

 * Target node is unreachable (e.g. due to hostname resolution, TCP connection or firewall issues)
 * CLI tool fails to authenticate with the server (e.g. due to CLI tool's Erlang cookie not matching that of the server)
 * Target node is not running

In addition to the diagnostics info below:

 * See the CLI, clustering and networking guides on https://rabbitmq.com/documentation.html to learn more
 * Consult server logs on node rabbit@mdmonirul
 * If target node is configured to use long node names, don't forget to use --longnames with CLI tools

DIAGNOSTICS
===========

attempted to contact: [rabbit@mdmonirul]

rabbit@mdmonirul:
  * unable to connect to epmd (port 4369) on mdmonirul: timeout (timed out)

Current node details:
 * node name: 'rabbitmqcli-49-rabbit@mdmonirul'
 * effective user's home directory: /var/lib/rabbitmq
 * Erlang cookie hash: 83qGOFOFZUNL0qnZprcJMg==_

[michaelklishin]

@dipualnur in order to help you we would need a bit of extra information. Can you please share the last 200 or so lines of the node log file?

If you had RabbitMQ 3.11 before and have upgraded it to 3.12, you must enable all feature flag (the Debian package itself does not do that at the moment, one day it will).

Temporarily (for one successful start) setting one environment variable should help:

RABBITMQ_FEATURE_FLAGS="restart_streams,stream_sac_coordinator_unblock_group,classic_mirrored_queue_version,direct_exchange_routing_v2,feature_flags_v2,listener_records_in_ets,stream_single_active_consumer,tracking_records_in_ets,classic_queue_type_delivery_support,stream_queue,user_limits,maintenance_mode_status,implicit_default_bindings,quorum_queue,virtual_host_metadata,drop_unroutable_metric,empty_basic_get_metric,delete_ra_cluster_mqtt_node,rabbit_mqtt_qos0_queue"

Alternatively, if it's a development node and you don't care about its existing data, you can wipe its data directory and it should boot. Then enable all feature flags using

rabbitmqctl enable_feature_flag all

[lukebakken]

Here is the error to investigate:

unable to connect to epmd (port 4369) on mdmonirul: timeout (timed out)

https://www.google.com/search?q=%22unable+to+connect+to+epmd+(port+4369)%22

I am not sure why this error would show up after an upgrade, however. What is the full output of these commands?

epmd -names
ss -4nl
netstat -an

Please save the output to a file and ATTACH the file to your response. Do NOT paste the output because it will be far too large.

[michaelklishin]

That's true. It could be a security-related change, they are not unheard of between upgrades. For example, a new set of firewall defaults that blocks epmd port access even for local processes.