Stripe Client Secret Mismatch Error with Connected Account PaymentIntent in Node.js

I'm setting up Stripe Connect payments on SvelteKit and encounter the following error when creating and using a PaymentIntent:

"> The client_secret provided does not match any associated PaymentIntent on this account. Ensure the publishable key used belongs to the same account that created the PaymentIntent."

I have confirmed that the client secret is generated using the matching secret key corresponding to my public key. I even tried using a sandbox account instead of a test environment, but the same error persists.

Below is my server-side code used to generate the client_secret:

TYPESCRIPTCopied
import { SECRET_STRIPE_KEY } from '$env/static/private';
const stripe = new Stripe(SECRET_STRIPE_KEY, {
    apiVersion: "2024-11-20.acacia" as "2024-10-28.acacia", // This is a type assertion
});

export async function GET() {
    const ticket_price = 45;
    const application_fee = 1;
    const paymentIntent = await stripe.paymentIntents.create({
        amount: ticket_price,
        currency: 'gbp',
        application_fee_amount: application_fee,
        automatic_payment_methods: {
            enabled: true
        }
    }, {
        stripeAccount: 'acct_1QWcgoDArWfcz7re',
    });

    return json({
        clientSecret: paymentIntent.client_secret
    }, { status: 200 });
}

On the client side, I'm using svelte-stripe along with stripe-js to render a payment form:

TYPESCRIPTCopied
<script lang="ts">
    import { onMount } from 'svelte';
    import { loadStripe } from '@stripe/stripe-js';
    import type { Stripe, StripeElements } from '@stripe/stripe-js';
    import { Elements, PaymentElement, LinkAuthenticationElement, Address } from 'svelte-stripe';
    import { PUBLIC_STRIPE_KEY } from '$env/static/public';

    let stripe: null | Stripe = null;
    let clientSecret: null | string = null;
    let elements: StripeElements | null | undefined;
    let processing = false;

    onMount(async () => {
        stripe = await loadStripe(PUBLIC_STRIPE_KEY, { apiVersion: "2024-11-20.acacia" as "2024-10-28.acacia" });
        clientSecret = await createPaymentIntent();
    });

    async function createPaymentIntent() {
        const response = await fetch('/api/stripe/payment', {
            method: 'GET',
            headers: {
                'content-type': 'application/json'
            }
        });

        const { clientSecret } = await response.json();
        return clientSecret;
    }

    async function submit() {
        // ...
    }

</script>

{#if clientSecret !== null}
    <Elements
        {stripe}
        {clientSecret}
        theme="flat"
        labels="floating"
        bind:elements
    >
        <form on:submit|preventDefault={submit}>
            <LinkAuthenticationElement />
            <PaymentElement />
            <Address mode="billing" />
            <button disabled={processing}>
                {#if processing}
                    Processing...
                {:else}
                    Pay
                {/if}
            </button>
        </form>
    </Elements>
{:else}
    Loading...
{/if}

When inspecting the network requests, all parameters appear correct. I triple-checked the keys and client secret, so I'm wondering if this is solely a Stripe issue. My Stripe logs show the failed request for the Elements session, but I don't see the corresponding request for creating the client secret:

BASHCopied
https://api.stripe.com/v1/elements/sessions?client_secret=pi_3QWcxADArWfcz7re023mkEqp_secret_mHQ6ErNxsy61qqAAp57FD1rIT&key=pk_test_69buoGS6vl82TpptRDix1WEr00LnbLWpxw&_stripe_version=2024-11-20.acacia&type=payment_intent&locale=en-US&referrer_host=localhost:5173&expand[0]=payment_method_preference.payment_intent.payment_method&stripe_js_id=bb0bb448-9ebf-46c9-b6e5-77e60c7f4016

client_secret=pi_3QWcxADArWfcz7re023mkEqp_secret_mHQ6ErNxsy61qqAAp57FD1rIT
key=pk_test_69buoGS6vl82TpptRDix1WEr00LnbLWpxw

Below is the error response from Stripe:

JSONCopied
{
  "error": {
    "message": "The client_secret provided does not match any associated PaymentIntent on this account. Ensure the publishable key used belongs to the same account that created the PaymentIntent.",
    "param": "client_secret",
    "request_log_url": "https://dashboard.stripe.com/test/logs/req_Gf29tN9FjPAYJe?t=1734350353",
    "type": "invalid_request_error"
  }
}

Notably, when I removed the "stripeAccount" option from the PaymentIntent creation, the error disappeared but the payment no longer functions as a connected payment. This leads me to believe that I must use the connected account's keys for both sides of the transaction for Stripe Connect payments. Could this mismatch between the connected account and the publishable key be the root of the issue?

If anyone has insights or solutions on aligning these keys correctly for connected payments, your help would be appreciated.