MQTT Broker listen messages randomly

[bastianfbr]

Bug Description

After working a lot with n8n, i did some workflows with MQTT Triggers. Everything worked fine before but now worfklows are randomly triggers. I have a program which send messages to topics i listen. Messages are really sent but triggers are 1/100 triggered... What can i do ? Sounds like listeners aren't always listening.

In addition, I have a custom MQTT trigger in a workflow that avoid listening to retained messages and when i want to enable it, i have this error :

To Reproduce

Create several workflows with MQTT Triggers
Activate all and see them not triggered

Expected behavior

Just want that everything works as expected : should be triggered every time a message is listened

Operating System

Windows 11

n8n Version

1.57.0

Node.js Version

18

Database

PostgreSQL

Execution mode

main (default)

[Joffcom]

Hey @bastianfbr,

We have created an internal ticket to look into this which we will be tracking as "GHC-229"

[Joffcom]

Hey @bastianfbr,

Are you using the same mqtt topic or different topics and how many do you get up to before seeing the issue?

[bastianfbr]

It was for the same topic

[Joffcom]

Hey @bastianfbr,

Typically I would expect one workflow and trigger per topic, Can you share a bit more info about what it is you are doing?

[tennox]

I am also having issues with my MQTT trigger.
First I also saw the max listeners warning in console, then figured I had a rather old n8n version and upgraded.
But still not working properly - it currently seems to trigger only on the first message, and only if I send it from cli laptop, but not from the MQTT sending node in n8n. Here's my workflow:

Nodes json:

{
  "meta": {
    "instanceId": "71cba87a424d172df0d2a5c5b532c51688885e58fc096bf267ef75427c03dd47"
  },
  "nodes": [
    {
      "parameters": {
        "topics": "zigbee2mqtt/dry-switch-heating",
        "options": {
          "jsonParseBody": false,
          "onlyMessage": false
        }
      },
      "id": "849978d3-619d-49b3-9905-9153b93a3bb7",
      "name": "on heater state",
      "type": "n8n-nodes-base.mqttTrigger",
      "typeVersion": 1,
      "position": [
        2140,
        1180
      ],
      "credentials": {
        "mqtt": {
          "id": "9sXSaJesebHLe5Sk",
          "name": "rose-MQTT"
        }
      }
    },
    {
      "parameters": {
        "topic": "zigbee2mqtt/dry-switch-heating/get/state",
        "sendInputData": false,
        "message": "=''",
        "options": {}
      },
      "id": "317cb6fa-98f3-484b-bbd7-b93136bff034",
      "name": "ask for state",
      "type": "n8n-nodes-base.mqtt",
      "typeVersion": 1,
      "position": [
        2140,
        1380
      ],
      "credentials": {
        "mqtt": {
          "id": "9sXSaJesebHLe5Sk",
          "name": "rose-MQTT"
        }
      }
    },
    {
      "parameters": {
        "rule": {
          "interval": [
            {
              "field": "minutes",
              "minutesInterval": 1
            }
          ]
        }
      },
      "id": "d1ca9269-f4ab-4498-b53c-4129dc2c1965",
      "name": "Val-Check schedule",
      "type": "n8n-nodes-base.scheduleTrigger",
      "typeVersion": 1.2,
      "position": [
        1960,
        1380
      ]
    }
  ],
  "connections": {
    "Val-Check schedule": {
      "main": [
        [
          {
            "node": "ask for state",
            "type": "main",
            "index": 0
          }
        ]
      ]
    }
  },
  "pinData": {}
}

[tennox]

Over night it started to sometimes trigger on messages - and seemingly with some kind of pattern - but I don't know what to make of it:
(my current workflow is set up to send telegram on each received message - but somehow it only triggers sometimes and seemingly only on state switches, but also there only sometimes... 😕 )

[tennox]

Reproduced the 'sometimes'-ness with a very simple workflow:

{
  "meta": {
    "instanceId": "71cba87a424d172df0d2a5c5b532c51688885e58fc096bf267ef75427c03dd47"
  },
  "nodes": [
    {
      "parameters": {
        "topics": "zigbee2mqtt/dry-switch-heating",
        "options": {}
      },
      "id": "4263a094-2c47-4c28-acd5-95ad4ee48d34",
      "name": "MQTT Trigger",
      "type": "n8n-nodes-base.mqttTrigger",
      "typeVersion": 1,
      "position": [
        720,
        560
      ],
      "credentials": {
        "mqtt": {
          "id": "9sXSaJesebHLe5Sk",
          "name": "rose-MQTT"
        }
      }
    },
    {
      "parameters": {
        "chatId": "90964282",
        "text": "={{ $json.topic }}\n{{ $json.message }}",
        "additionalFields": {
          "appendAttribution": false,
          "parse_mode": "HTML"
        }
      },
      "id": "4017f48c-ae47-4aa1-98a5-d48a679f2b84",
      "name": "Telegram",
      "type": "n8n-nodes-base.telegram",
      "typeVersion": 1.2,
      "position": [
        940,
        560
      ],
      "credentials": {
        "telegramApi": {
          "id": "y5bFEQpcxcfTzrqZ",
          "name": "Rosenhof Bot"
        }
      }
    }
  ],
  "connections": {
    "MQTT Trigger": {
      "main": [
        [
          {
            "node": "Telegram",
            "type": "main",
            "index": 0
          }
        ]
      ]
    }
  },
  "pinData": {}
}