Using NR v3.0.2 I'm using a MQTT in Node and keep getting the messages received twice. It might be a trivial issue... tried changing the QOS from the default 0 to 2 but didn't change anything. Thought it was the broker but ruled it out as other clients just receive the message once. This is anno…

[image] Colin: I vaguely remember a bug like that It is a feature :wink: There is a technical reason under the hood that I try to explain below however, if you have a v5 capable broker, switching to v5 will avoid this issue. In as short a terms I can, the MQTT client provides single stream…

If you add a Debug node to the MQTT In node, do you get two messages there? If not then I would suggest that your MQTT Sender might be sending the message twice as you have eliminated the broker.

I think there must be a typo in your post somewhere @mudwalker Also the OP days that other clients only receive one message. But we do need to know what is seen in a debug node directly on the MQTT In Node

By MQTT Sender, I mean the originating MQTT device. Of course, the OP may mean that all the MQTT messages come from the same device, but that didn't seem absolutely clear to me. If they do all come from the same origin, sorry for the confusion.

Ah yes, I see what you mean. @PPASSL if another client subscribers to exactly the same topic does that client see just one message?

Interesting to notice that the _msgid: are different between the duplicates. Where is that ID created? By the node?

In case you ask, the MQTT in node looks like this: [NR-MQTTBug-2] and the debug node: [NR-MQTTBug-3]

how many subscriptions do you have and what are they? For example, I can see a subscription to events/# - is that all? or do you also subscribe to events/testIP? Once more question, what broker (what version broker) are you using?

@Steve-Mcl you got it! I had another node subscribed to events/testIP (it was on different flow!) As soon as I disable that flow I'm now seeing NO duplication. Can someone explain? The duplication doesn't seem correct to me because it originates from the same debug node... To answer you about t…

Do you mean that the second mqtt node was causing duplicated output from the first? I vaguely remember a bug like that. What version of node red are you using? Look at the bottom of the drop down menu in the editor.

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MQTT node - messages received twice!?

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PPASSL 16 November 2022 18:12 6

All other clients (Python, iOS MQTT tool) just get one message.

My MQTT node subscribes to 'events/#'
Let me try to upload the capture of the debug node:

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MQTT node - messages received twice!?

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