Lightning Out : Error 404, Blocked by CORS

Question

To test Lightning Out on an external site, I use the application created in the "Aura Components Basics" module: expensesApp

This one works very well the proof in image:

Pour To make my application available with lightning out, I helped myself to this blog: https://newstechnologystuff.com/2019/05/28/use-lightning-web-components-in-lightning-out/

1. I add the url of site which must integrate my application in the CORS
2. I created a new dedicated application for lightning out "LightOutApp"

    <aura:application access="GLOBAL" extends="ltng:outApp" implements="ltng:allowGuestAccess">
    <aura:dependency resource="c:expenses" type="COMPONENT"/>
    </aura:application>

Here's the code for my expenses component :

```Lightning Aura Components
<aura:component controller="ExpensesController">

<aura:attribute name="expenses" type="Expense__c[]"/>

<aura:handler name="updateExpense" event="c:expensesItemUpdate"
              action="{!c.handleUpdateExpense}"/>
<aura:handler name="createExpense" event="c:expensesItemUpdate"
              action="{!c.handleCreateExpense}"/>

<aura:handler name="init" action="{!c.doInit}" value="{!this}"/>

<!-- PAGE HEADER -->
<lightning:layout class="slds-page-header slds-page-header--object-home">
    <lightning:layoutItem>
        <lightning:icon iconName="standard:scan_card" alternativeText="My Expenses"/>
    </lightning:layoutItem>
    <lightning:layoutItem padding="horizontal-small">
        <div class="page-section page-header">
            <h1 class="slds-text-heading--label">Expenses</h1>
            <h2 class="slds-text-heading--medium">My Expenses</h2>
        </div>
    </lightning:layoutItem>
</lightning:layout>
<!-- / PAGE HEADER -->
<!-- NEW EXPENSE FORM -->
<lightning:layout >
    <lightning:layoutItem padding="around-small" size="6">
        <c:expenseForm/>
    </lightning:layoutItem>
</lightning:layout>

<lightning:layout>
    <lightning:layoutItem padding="around-small" size="6">
        <c:expensesList expenses="{!v.expenses}"/>
    </lightning:layoutItem>
    <lightning:layoutItem padding="around-small" size="6">
        Put something cool here
    </lightning:layoutItem>
</lightning:layout>

3. I added the code JS on the page of the site which must display my component, here :

$Lightning.use("c:LightOutApp", function() { $Lightning.createComponent("c:expenses", { authToken: "3MVG9Ve.2wqUVx_Z3nFMx_ytwdm0WnBAnowDB1mvO.d6trt4DDAipWp7tno3.lNL2YWT.jj0h0MHoxKTObe3D" }, "lightning", function(cmp) { console.log("component was created"); // do some stuff } ); }, 'https://playful-fox-o26ov9-dev-ed.lightning.force.com/' );

but when I load the page, I always get the following error in my chrome JS console:

Access to XMLHttpRequest at 'https://playful-fox-o26ov9-dev-ed.lightning.force.com//c/LightOutApp.app?aura.format=JSON&aura.formatAdapter=LIGHTNING_OUT' from origin 'https://webidetesting6929559-p2000088220trial.dispatcher.hanatrial.ondemand.com' has been blocked by CORS policy: No 'Access-Control-Allow-Origin' header is present on the requested resource. /webapp/resources/sap/ui/core/messagebundle_fr_FR.properties:1 Failed to load resource: the server responded with a status of 404 ()

I forgot something ? The syntax of my code is not good?

You can test the integration and see the error message at this address :

https://nashle.github.io/lightningout/

---

Here is the picture of my CORS:

I wonder if this comes from the configuration of the Online Application or the fact that it may be necessary to activate community. Do you know what settings I need to fill in when I create my Connected App?

So you need to configure a community to access my lightning-out application on a third-party portal that does not have to be hosted by the community to provide access rights?

I implement ltng: allowGuestAccess "to Share Lightning App with Non-Authenticaded Users.

Aloha!

Answer 1

I ran into this same issue today. I had not input a name for the community in the URL string available from the Administration area in Workspaces.

Once I added a name at the end of the URL string and updated my scripts, the lightning out app started writing to the console log the debug lines I added to ensure it was working from my test site.

Answer 2

This morning, I used Lightning Out with the Lightning Web Components and there, magically, it works perfectly!

So I will train at the LWC.

I would like to understand why integration does not work.

If anyone understands where it comes from, I'm waiting for you here!