I have an LWC FSC (flow screen component).

I am trying to subscribe to a CDC event, but the subscription never seems to execute.

The same LWC when displayed on a lightning record page does subscribe to the CDC event.

Is there a restriction that stops FSCs from being able to subscribe to CDC events?

import { LightningElement } from 'lwc';
import { subscribe } from 'lightning/empApi';

export default class MySubscribeTest extends LightningElement {


    connectedCallback() {
        console.log('this definitely runs');
        const messageCallback = (response) => {
            console.log('New message received: ', JSON.stringify(response));
        // the then/catch blocks are never executed
        subscribe('/data/My_Custom_Object__ChangeEvent', -1, messageCallback)
        .then((response) => {
            // Response contains the subscription information on subscribe call
                'Subscription request sent to: ',
            this.subscription = response;
        .catch((error) => {

1 Answer 1


Turns out this works fine, but it does NOT work when in debug mode of the flow.

Make sure the flow is saved/activated, then launch it as a user would.

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