mosquitto does not seem to like the following options for persistence.

# Persistence configuration
persistence true
persistence_location /data/qos/
persistent_client_expiration 8h

The /data/qos does exist and permissions have been set.

sudo chown mosquitto:mosquitto /data/qos

The persistence configuration options are in a file persist.conf placed under /etc/mosquitto/conf.d directory. Before copying, I am stopping the broker and starting it again after copying using commands like this:

sudo service mosquitto stop
sudo service mosquitto start

The /var/log/mosquitto/mosquitto.log does not give any clue about what could be the issue.

So, what's wrong with the options provided above for persistence?

  • What happens if you stop the service and manually start su mosquitto -c mosquitto -c /etc/mosquitto/mosquitto.conf
    – hardillb
    Commented Jun 27, 2018 at 18:46
  • Also are you sure it doesn't start or is it just not creating the persistence file at startup?
    – hardillb
    Commented Jun 27, 2018 at 20:06
  • @hardillb I do recall starting mosquitto successfully with /usr/bin/mosquitto -c /etc/mosquitto/mosquitto.conf i.e. without the switch user. Yes, mosquitto never started; no processes are listed in ps -ef | grep mosq. BTW, what is procedure in general? Stop broker, copy .conf files into /etc/mosquitto/conf.d folder and then start broker? Commented Jun 28, 2018 at 1:14

1 Answer 1


As mentioned in the post above, the persistence configuration options were provided in a separate file - persist.conf placed under /etc/mosquitto/conf.d directory. However, there are persistence options already present in /etc/mosquitto/mosquitto.conf. Once I removed these, the settings in persist.conf went through.

It would have been nice of mosquitto to warn of such conflicts.

  • Mosquitto does flag up duplicate values when it fails to start (at least at v1.4.x) Error: Duplicate persistence_file value in configuration.
    – hardillb
    Commented Jun 28, 2018 at 11:06
  • Hmm...I think I am at 1.4 as I wanted the compiled version of websockets from Ubuntu ppa. Don't recall that message. Maybe I missed? Commented Jun 28, 2018 at 11:15

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