# Catch errors for mqtt out

**URL:** <https://discourse.nodered.org/t/catch-errors-for-mqtt-out/94536>\
**Category:** General\
**Tags:** mqtt\
**Created:** [11 January 2025 17:12 UTC](https://discourse.nodered.org/t/catch-errors-for-mqtt-out/94536 "2025-01-11T17:12:41Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![wannestal](https://avatars.discourse-cdn.com/v4/letter/w/2acd7d/32.png) [@wannestal](https://discourse.nodered.org/u/wannestal)\
**Post date:** [11 January 2025 17:12 UTC](https://discourse.nodered.org/t/catch-errors-for-mqtt-out/94536/1 "2025-01-11T17:12:41Z")

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I use node MQTT OUT to send messages to a server. This is working well, but I want to add a buffer if for example the receiving server fails. Therefore I like to use the CATCH node, but it does not react on a connection failure of MQTT OUT. I am sure that I select the correct node to react on. Any suggestions to be able to catch such a failure?

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**Author:** ![E1cid](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/e1cid/32/77971_2.png) [@E1cid](https://discourse.nodered.org/u/E1cid)\
**Post date:** [11 January 2025 17:20 UTC](https://discourse.nodered.org/t/catch-errors-for-mqtt-out/94536/2 "2025-01-11T17:20:20Z")

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I thought this thread may give you what you require or atleast some ideas. [[Announce] Improved Guaranteed Delivery flow](https://discourse.nodered.org/t/announce-improved-guaranteed-delivery-flow/39877)

[Edit]  
Here is link to Colins latest version [node-red-guaranteed-delivery (node) - Node-RED](https://flows.nodered.org/node/@colinl/node-red-guaranteed-delivery)

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**Author:** ![Colin](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/colin/32/17040_2.png) [@Colin](https://discourse.nodered.org/u/Colin)\
**Post date:** [11 January 2025 17:50 UTC](https://discourse.nodered.org/t/catch-errors-for-mqtt-out/94536/3 "2025-01-11T17:50:30Z")

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In fact that has been superceded by @colinl/node-red-guaranteed-delivery, which includes an example of how to use it with mqtt.

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**Author:** ![jbudd](https://avatars.discourse-cdn.com/v4/letter/j/5f8ce5/32.png) [@jbudd](https://discourse.nodered.org/u/jbudd)\
**Post date:** [11 January 2025 19:28 UTC](https://discourse.nodered.org/t/catch-errors-for-mqtt-out/94536/4 "2025-01-11T19:28:31Z")

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You can also look at MQTT "Last Will &Testament" messages.  
They are set up in the Node-red MQTT broker config. and get sent when it first connects to the broker, but don't "arrive" unless the connection drops.

ie After the connection to the broker goes down, and a timeout period has elapsed (default 60s?) a message, which could be "MQTT lost contact" _seems_ to arrive with the LWT topic.

Hivemq have a video about LWT [here](https://www.youtube.com/watch?v=dNy9GEXngoE)

Edit - I'm currently watching that video. Perhaps I misunderstand who gets the LWT message when a client disconnects.

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**Author:** ![system](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/1X/d073cd938eafa2e558d7c2cd59003b3ef4963033.png) [@system](https://discourse.nodered.org/u/system)\
**Post date:** [11 April 2025 19:29 UTC](https://discourse.nodered.org/t/catch-errors-for-mqtt-out/94536/5 "2025-04-11T19:29:02Z")

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