How to catch an errors from Node-RED nodes

September 2, 2023

In this post i will share ,how to use Node Red “Catch Error” node to catch error log .

A Catch Node can be used to monitor errors that occur within nodes residing in a flow.

Lets Build a Catch Error Node

In order to test the Catch Error Node, we will build a node to add up 2 Variable using a function node.

In this Function node name as ” Add First and third Number ” 1 of the 2 variable are not being declared .

Thus when the Function try to add the first variable to the second variable there will be an error .

This Error will catch by the catch node

Drag out an inject node and configure as below

Build the Add Function Node

Drag out the Function Node and paste the Code below inside the Function Node at the On Message Tab Area.

var firstNumber = flow.get(‘firstNumber’);

//var thirdNumber = flow.get(‘thirdNumber’);

// Perform addition

var total = firstNumber + thirdNumber;

// Set the result in the output message

msg.total = total;

// Return the modified message

return msg;

Drag out a Debug node configure as below.

When Done Joint All the Nodes

Configure Catch Node to Monitor the Function node

When done drag a debug node configure as below

Lastly joint the Nodes

Trigger “Add”

Observe the Debug Message