Cannot start rabbitmq service on Debian

[Dinizzzka]

Hello.
I had to install RabbitMQ on Debian Trixie. I found manual here: Apt with Team RabbitMQ's Repositories: a Quick Start Script.
I did everything according to the instructions. Installation was successfull. No errors. But when I tried to start rabbitmq-server I got an error. Looked for logs in dir /var/log/rabbitmq - no logs. Run command sudo journalctl -xeu rabbitmq-server.service that supplied following output:

debian rabbitmq-server[573494]:     rabbit_feature_flags:try_to_read_enabled_feature_flags_list/0, line 1216 \n
debian rabbitmq-server[573494]:     rabbit_feature_flags:read_enabled_feature_flags_list/0, line 1202  \n
debian rabbitmq-server[573494]:     rabbit_ff_registry_factory:initialize_registry/1, line 109  \n
debian rabbitmq-server[573494]:     rabbit_prelaunch_feature_flags:setup/1, line 3
debian rabbitmq-server[573494]:     rabbit:run_prelaunch_second_phase/0, line 381
debian rabbitmq-server[573494]:     rabbit:start/2, line 932
debian rabbitmq-server[573494]:     application_master:start_it_old/4, line 295
debian rabbitmq-server[573494]: 2025-09-05 16:57:38.498938+03:00 [notice] <0.45.0> Application rabbit exited with reason: {{case_clause,{ok,[]}},{rabbit,start,[normal,[]>
debian rabbitmq-server[573494]: {exit,terminating,[{application_controller,call,2,[{file,"application_controller.erl"},{line,511}]},{application,'-ensure_all_started/3-l>
debian rabbitmq-server[573494]: 2025-09-05 16:57:38.499100+03:00 [error] <0.210.0>   crasher:
debian rabbitmq-server[573494]: 2025-09-05 16:57:38.499100+03:00 [error] <0.210.0>     initial call: application_master:init/3
debian rabbitmq-server[573494]: 2025-09-05 16:57:38.499100+03:00 [error] <0.210.0>     pid: <0.210.0>
debian rabbitmq-server[573494]: 2025-09-05 16:57:38.499100+03:00 [error] <0.210.0>     registered_name: []
debian rabbitmq-server[573494]: 2025-09-05 16:57:38.499100+03:00 [error] <0.210.0>     exception exit: {{case_clause,{ok,[]}},{rabbit,start,[normal,[]]}}
debian rabbitmq-server[573494]: 2025-09-05 16:57:38.499100+03:00 [error] <0.210.0>       in function  application_master:init/3 (application_master.erl, line 143)
debian rabbitmq-server[573494]: 2025-09-05 16:57:38.499100+03:00 [error] <0.210.0>     ancestors: [application_controller,<0.10.0>]
debian rabbitmq-server[573494]: 2025-09-05 16:57:38.499100+03:00 [error] <0.210.0>     message_queue_len: 1
debian rabbitmq-server[573494]: 2025-09-05 16:57:38.499100+03:00 [error] <0.210.0>     messages: [{'EXIT',<0.211.0>,normal}]
debian rabbitmq-server[573494]: 2025-09-05 16:57:38.499100+03:00 [error] <0.210.0>     links: [<0.45.0>]
debian rabbitmq-server[573494]: 2025-09-05 16:57:38.499100+03:00 [error] <0.210.0>     dictionary: []
debian rabbitmq-server[573494]: 2025-09-05 16:57:38.499100+03:00 [error] <0.210.0>     trap_exit: true
debian rabbitmq-server[573494]: 2025-09-05 16:57:38.499100+03:00 [error] <0.210.0>     status: running
debian rabbitmq-server[573494]: 2025-09-05 16:57:38.499100+03:00 [error] <0.210.0>     heap_size: 233
debian rabbitmq-server[573494]: 2025-09-05 16:57:38.499100+03:00 [error] <0.210.0>     stack_size: 29
debian rabbitmq-server[573494]: 2025-09-05 16:57:38.499100+03:00 [error] <0.210.0>     reductions: 70
debian rabbitmq-server[573494]: 2025-09-05 16:57:38.499100+03:00 [error] <0.210.0>   neighbours:
debian rabbitmq-server[573494]: 2025-09-05 16:57:38.499100+03:00 [error] <0.210.0>
debian rabbitmq-server[573494]: Kernel pid terminated (application_controller) ("{application_start_failure,rabbit,{{case_clause,{ok,[]}},{rabbit,start,[normal,[]]}}}")
debian rabbitmq-server[573494]:
debian rabbitmq-server[573494]: Crash dump is being written to: erl_crash.dump...done
debian systemd[1]: rabbitmq-server.service: Main process exited, code=exited, status=1/FAILURE

Have no idea what is the reason of the issue.

[michaelklishin]

@Dinizzzka there won't be any errors upon installation because on modern Debian, services are not started automatically by design, and the RabbitMQ package adheres to that best practice.

You have cut a key part from the logs. We do not guess in this community.

You can be upgrading a cluster that did not have all feature flags enabled, or all graduated/required feature flags enabled, e.g. from 3.12 to 4.x directly, which is not a supported combination for upgrades.

[Dinizzzka]

Here is rest part of log:

Subject: Unit process exited
Defined-By: systemd
Support: https://www.debian.org/support
An ExecStart= process belonging to unit rabbitmq-server.service has exited.
The process' exit code is 'exited' and its exit status is 1.
сен 05 19:36:18 debian systemd[1]: rabbitmq-server.service: Failed with result 'exit-code'.
Subject: Unit failed
Defined-By: systemd
Support: https://www.debian.org/support
The unit rabbitmq-server.service has entered the 'failed' state with result 'exit-code'.

[michaelklishin]

@Dinizzzka can you share the entire RabbitMQ log (not a systemd service/unit log)? Please make sure to redact all non-localhost hostnames and IP addresses.

[Dinizzzka]

Unfortunately there no rabbitmq logs. Directory /var/log/rabbitmq is empty.
It's strange but there even no rabbitmq.config file on filesystem.

[michaelklishin]

@Dinizzzka that makes sense and matches my comment below. The node terminates very early. I doubt it can be an Erlang version incompatibility because Debian packages correctly specify a supported set of dependencies.

Something in your environment violates basic expectations for a node, or a security tool prevents the node from starting, or the node cannot access one of its data directories.

[michaelklishin]

According to the portion of the log there is, the {ok, []}, the main startup function, rabbit:start_it/1, uses application:ensure_all_started/1 to start rabbit_prelaunch and then RabbitMQ itself.

Then application_master:init/3 runs into an error of sorts and masks whatever failure it runs into by using exit/1 (throwing an exception).

This is not something common to see but I cannot guess what specifically has tripped up this node.
My best guess is that one of the fundamental assumptions of RabbitMQ nodes or the good old "some files were inaccessible to the node" (in the case of a Debian package, likely due to SELinux or something like that).