[Bug] createPayPalSubscriptionPaymentSession failing intermittently

[alexedwardjones]

Library used

Direct script integration — https://www.paypal.com/web-sdk/v6/core

🐞 Describe the Bug

Intermittently, authenticated PayPal users are redirected to an error screen at https://www.paypal.com/webapps/hermes/error?token=....

🔬 Minimal Reproduction

const sdkInstance = await window.paypal.createInstance({
    clientId: '...',
    components: ['paypal-subscriptions'],
});

const session = await sdkInstance.createPayPalSubscriptionPaymentSession({
    onApprove: async () => { /* redirect to success */ },
    onCancel: () => { /* reset UI */ },
    onError: () => { /* show error */ },                                         
});
                                                                                 
// On button click:                                       
await session.start({ presentationMode: 'popup' }, subscriptionPromise);
// where subscriptionPromise resolves to { subscriptionId }

😕 Actual Behavior

Intermittently, authenticated PayPal users are routed through https://www.paypal.com/web-sdk/content/en-GB/paypal-loading and then immediately redirected to an error screen at https://www.paypal.com/webapps/hermes/error?token=... (screenshot above). The popup never proceeds past the loading page when this occurs. The failure is inconsistent, it doesn't happen on every attempt, and I haven't been able to identify a pattern.

🤔 Expected Behavior

The subscription popup should open successfully and allow the authenticated user to complete the payment, consistent with the behaviour seen for one-time payments using createPayPalOneTimePaymentSession which is working fine for us.

🌍 Environment

• Node.js/npm: -
• OS: -
• Browser: -

➕ Additional Context

We can't find createPayPalSubscriptionPaymentSession referenced anywhere in the official v6 documentation, the upgrade guide, or the https://github.com/paypal-examples/v6-web-sdk-sample-integration (which only covers one-time payments). The v6 docs list createPayPalOneTimePaymentSession, createPayLaterOneTimePaymentSession, createPayPalCreditOneTimePaymentSession, and createFastlane but nothing for subscriptions.

Is createPayPalSubscriptionPaymentSession an officially supported and stable API?
Is the paypal-subscriptions component considered production-ready?

[bywood]

@alexedwardjones Can you share any subscription IDs or paypal-debug-id values?

Also, can you try checking the eligibility using sdkInstance.findEligibleMethods? We have an example integration here: https://github.com/paypal-examples/v6-web-sdk-sample-integration/blob/main/client/components/paypalSubscriptions/html/src/recommended/app.js#L27-L34

You can try out this example here: https://v6-web-sdk-sample-integration-server.fly.dev/client/components/paypalSubscriptions/html/src/recommended/index.html

The paypal-subscription component is considered production-ready. The official docs just haven't been updated yet.

[alexedwardjones]

@bywood Thanks for getting back to me.

I've tried the hosted v6-web-sdk-sample-integration and have exactly the same issue.

I've tested this in Chrome, Firefox and Safari.

Steps to reproduce consistently:

1. Open the example you linked in an incognito window
2. Click the subscribe button to open the popup modal
3. Log in with sandbox credentials
4. Error screen

If you try these steps, is it working for you?
Do you have a different set of fake sandbox credentials I could try? 🤷

[bywood]

@alexedwardjones I was able to reproduce the issue with a UK test account. We're looking into it now. Thanks for bringing this to our attention.

[alexedwardjones]

Glad to hear it's not just me. Thanks for looking into it.