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I am using django-celery for my django project. Last day I have changed my computer's hostname (I am using Ubuntu 12.04, edited file '/etc/hostname'), and after next restart django-celery was failing with error 

Consumer: Connection Error: [Errno 111] Connection refused. Trying again in 4 seconds...

After some research on this error I could find that, changing my host name caused this error from here. My rabbitmq startup log shows

file: /var/log/rabbitmq/startup_log

Activating RabbitMQ plugins ...

********************************************************************************
********************************************************************************

0 plugins activated:

ERROR: epmd error for host "jinesh": nxdomain (non-existing domain)

My startup_err file is empty.

when I run 

root@jinesh:/home/jinesh# rabbitmqctl list_users
Listing users ...
Error: unable to connect to node rabbit@jinesh: nodedown

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

nodes in question: [rabbit@jinesh]

hosts, their running nodes and ports:
- unable to connect to epmd on jinesh: nxdomain

current node details:
- node name: rabbitmqctl4956@jinesh
- home dir: /var/lib/rabbitmq
- cookie hash: RGhmB2JR1LbZ57j7xWWTxg==

I hope changing the nodename may fix this issue. But I couldn't found a way to do this. Anyone have idea about how solve this issue?

update

while changing hostname you have to change both /etc/hostname and /etc/hosts files.

I reinstalled rabbitmq and solved this issue, Will answer this question.

Jinesh
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  • On centos/rhel, if you rename your network interfaces via /etc/udev/rules/70-persistant-net.rules and reboot --> doing so will also cause you to get an error message from `rabbitmqctl status` "unable to connect to epmd". --> The fix is the same as [the accepted answer by @RichardHFung for this question](http://stackoverflow.com/questions/14659335/rabbitmq-server-fails-to-start-after-hostname-has-changed-for-first-time/16973026#16973026). – Trevor Boyd Smith Mar 02 '16 at 16:58
  • "systemctl restart rabbitmq-server.service" solved the same issue I had. – Hem Oct 03 '16 at 15:22
  • If on Ubuntu 16.04 or 18.04, do NOT install RabbitMQ via the repository (they're outdated). Head here https://www.rabbitmq.com/install-debian.html and save yourself some headache down the line, by installing both Erlang and RabbitMQ from one of the proposed repositories. I had a while ago installed Erlang from erlang solutions and had much later installed RabbitMQ via its Ubuntu repo and it originally worked without fuss. After a recent upgrade something went wrong and I spent 5 hours trying to fix it to no avail. I removed both packages and reinstalled Bintray's versions as explained. Fixed. – Michael Ekoka Mar 10 '19 at 04:33

14 Answers14

57

Remove the old installation of RabbitMQ to fix this problem. Here are steps to reinstall RabbitMQ. These commands are run as the root user:

  1. Stop RabbitMQ: rabbitmqctl stop

  2. Change /etc/hosts

  3. Change /etc/hostname

  4. Uninstall old RabbitMQ: dpkg -P rabbitmq-server

  5. Remove RabbitMQ’s database: rm -rf /var/lib/rabbitmq

  6. Find erlang’s process that is running rabbit: ps ax | grep rabbit

  7. Kill the listed process

  8. Reinstall RabbitMQ: apt-get install rabbitmq-server

I wrote about these steps on my blog.

REVISION

I moved my blog to a new website.

Richard H Fung
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  • Note that I didn't have to stop rabbit (because it wasn't running) or remove the `/var/lib/rabbitmq` folder (because it wasn't there); YMMV. – Roger Lipscombe Jul 02 '14 at 13:49
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    on ubuntu (14.04.1 LTS) this did not work for me. I needed to `apt-get purge rabbitmq-server` and then run `apt-get install rabbitmq-server` to get it all working again after a hostname change. – Mike McMahon Feb 13 '15 at 21:06
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    RabbitMQ breaks for no good reason, and the only way to fix it is to uninstall and reinstall?This is alarming... – Cerin Apr 07 '15 at 17:24
  • Neither the manual instructions nor the `apt-get` instructions worked for me. As of yet, still no solution. Is this an erlang problem? – jmvbxx Oct 27 '15 at 22:54
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    Anyway of doing this without losing data? – cevaris Nov 20 '15 at 03:16
  • my problem was that there was an erlang process running, killed it and rabbit started as normal. – Alex R Jan 28 '16 at 13:15
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    i gave downvote because of solution is not a real solution. what if i change hostname again? remove rabbit again, install again .... – tersakyan Jun 28 '16 at 09:38
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    Check @Kishor Pawar answer if you don't want to lose data – Mehdi Yedes Mar 14 '17 at 16:19
43

Thanks to Richard H Fung.

His steps helped me to solve this issue.

But I did not have to re-install the rabbitmq.

When I opened my /etc/hosts file I found that IP assigned to my hostname is different than the actual ip(192.168.1.200 [static]). 

#/etc/hosts  
127.0.0.1       localhost  
192.168.1.115   HOSTNAME

so I just changed IP address to 192.168.1.200 in my /etc/hosts file and it worked fine.

Kishor Pawar
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    this is the exact situation i had and same solution worked - no need to reinstall and fixed ip and worked – naoko Jan 03 '15 at 04:49
  • This should be accepted as the correct solution. On xenial I had /etc/hosts associating a GloballyRoutableIP with the `hostname` name (not fqdn), and found that associating the NetworkTenIP with that name repaired epmd. Killing epmd and restarting rabbit sufficed. – J_H Dec 23 '17 at 21:29
  • Phew! Didn't have to re-install either. My issue after changing the hostname was that I don't use a FQDN in /etc/hostname. This is OK, but you then need to put that short alias in `/etc/hosts` for 127.0.0.1 or the erlang system can't resolve it. *I did however loose all queue contents*, presumably that store is associated with the old hostname. Possibly this could be solved by putting an IP address in the conf file... – CodeClown42 Mar 24 '22 at 20:29
25

Richard's answer is good, but you might lose some information in the rabbitmq queues. The following is a possible way to preserve the previous setup of rabbitmq with the new host name.

A Short Answer:

If you want to keep the new host name change, then you can create a rabbitmq-env.conf files in /etc/rabbitmq that references the old host name and all should be good. The following is what should be in the rabbitmq-env.conf file:

NODENAME=rabbit@OLDHOSTNAME

After adding the config file, restart the rabbitmq server then you should be good. (e.g. service rabbitmq-server restart (might need a sudo with ubuntu))

For more details you can read from the rabbitmq website: https://www.rabbitmq.com/man/rabbitmq-env.conf.5.man.html

More Details About the Answer:

I had a similar hostname issues using CentOS... The root issue was when rabbit installs, it references the current host name at the time of install. Since this is a rabbitmq thing, the solution should work for other linux flavors. If you want to see the full answer, you can see it at: rabbtimqadmin - Could not connect: [Errno -2] Name or service not known

Community
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James Oravec
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    This helped me. I updated to the latest version of rabbitmq (3.6.6-1) on ArchLinux and was unable to start it. Took a look in `/etc/rabbitmq/rabbitmq-env.conf` and 'lo and behold, the `NODENAME` was all wrong. Instead of `rabbit@machine`, it had become `rabbit@machine@machine` during the upgrade. A simple removal of the last `@machine` fixed the problem. – qwelyt Dec 01 '16 at 07:21
  • This is the proper answer IMHO...@Chewtoy it's even in the Arch wiki :-D https://wiki.archlinux.org/index.php/Rabbitmq#Changed_hostname – danidee Dec 23 '17 at 12:05
  • So awesome!. Thank you. I changed my hostname and I didn't wanted to lose any information (usernames, etc). The env.conf file fixed my problem. – mFlorin Feb 16 '18 at 13:45
  • Where is this file on Windows? – TheRealChx101 Jul 20 '19 at 20:41
6

You could solve this problem by either deleting the erlang mnesia database associated with rabbitmq or reinstalling rabbitmq.

I got hint for first solution from rabbitmq mailing list. Excerpt from answer, The Erlang Mnesia database is host specific (because it is a distributed DB). The simplest way to get you fixed is to clear out the database dir.

The second method is the easiest way (not recommend though). To uninstall do 

dpkg -P rabbitmq-server

You can refer this link if you would like to know more about installing/removing debian packages.

Jinesh
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5

On Windows, the issue I was facing was due to the McAfee firewall. The exact error was:

epmd error for host "<HOSTNAME>": address (cannot connect to host/port)

It started working as soon as I disabled the firewall

Pang
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Gautam
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4

Remove RabbitMQ database: rm -rf /var/lib/rabbitmq/*

This action solves the problem. I believe somewhere in dumps stored a record with correspondence of nodes host names and ips. This fact causes contradiction if some hosts changed unexpectedly.

I159
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3

My solution was to check and correct the $HOSTNAME and /etc/hostname. It turned out that my router was a little confused and gave me a wrong hostname domain. After restarting this one, I called export HOSTNAME=the.correct.hostname and my rabbit runs without restarting the server os.

Eduardo Cuomo
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bert
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3

In my case I did not have a following entry in /etc/hosts:

127.0.0.1 <hostname>

where <hostname> is the hostname of my machine (as given by the hostname command). After adding that line, RabbitMQ started successfully. I did not have any earlier installations of RabbitMQ.

Adam Michalik
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  • For me, this was the answer which worked. However I'm still puzzled why the default `127.0.0.1 localhost.localadmin localhost` line didn't resolve to the appropriate nodename. Thank you very much! – Letokteren May 10 '17 at 09:58
2

When on Windows (sorry about that - I understand the topic is for Ubuntu) just reinstall the RabbitMQ service:

rabbitmq-service.bat remove
rabbitmq-service.bat install

The script is located at C:\Program Files\RabbitMQ Server\rabbitmq_server-<version>\sbin folder.

Or may be just changing the value of HKEY_LOCAL_MACHINE\SOFTWARE\Ericsson\Erlang\ErlSrv\1.1\RabbitMQ\@SName is enough.

Clues: https://github.com/rabbitmq/rabbitmq-server/issues/620

Vertigo
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1

To solve this problem, I changed my /etc/hostname file with the new hostname then restarted the machine. After that, I ran rm -rf /var/lib/rabbitmq/mnesia/*

Then restarted the service : sudo service rabbitmq-server restart

At this point, it worked for me. If it still don't work, modify the file /etc/rabbitmq/rabbitmq-env.conf by adding those informations :

NODENAME=rabbit@YOUR_NEW_HOSTNAME
NODE_IP_ADDRESS=127.0.0.1
NODE_PORT=5672

Then restart the service : sudo service rabbitmq-server restart

Hope it helps.

Sébastien Crettaz
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0

I had the same problem and doing the steps Richard H Fung provided didn't helped me. I also had to uninstall these packages: erlang erlang-epmd rabbitmq-server

zypper remove erlang erlang-epmd rabbitmq-server
rm -rf /var/lib/rabbitmq/*
zypper install erlang erlang-epmd rabbitmq-server
systemctl enable rabbitmq-server.service
systemctl start rabbitmq-server.service

If you have another OS than openSUSE just use your package manager to remove these packages (e.g. apt-get)

Peter
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0

  1. Change to old hostname.

    • sudo hostnamectl set-hostname (old_hostname)

  2. Start rabbitmq-server and stop again.

    • sudo systemctl start rabbitmq-server.service
    • sudo systemctl stop rabbitmq-server.service

  3. Change to new hostname.

    • sudo hostnamectl set-hostname (new_hostname)

  4. Start rabbitmq-server.

    • sudo systemctl start rabbitmq-server.service
송영재
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-1

The only solution which work for me: install erlang & rabbitmq from deb, so:

First remove:

apt-get purge rabbitmq-server
apt-get purge erlang
apt-get autoremove
reboot

After install wget:

sudo apt-get -y install socat logrotate init-system-helpers adduser
sudo apt-get -y install wget

Install erlang:

wget https://packages.erlang-solutions.com/erlang-solutions_1.0_all.deb
sudo dpkg -i erlang-solutions_1.0_all.deb
sudo apt-get update
sudo apt-get install erlang

Install rabbitmq:

sudo apt-get update
wget https://github.com/rabbitmq/rabbitmq-server/releases/download/v3.7.17/rabbitmq-server_3.7.17-1_all.deb
sudo dpkg -i rabbitmq-server_3.7.17-1_all.deb
rm rabbitmq-server_3.7.17-1_all.deb
ZeroProcess
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-2

Check qpidd daemon, it could be also already hogging the port that rabbitmq needs.

sudo netstat -lnp
Brian
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ash zak
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