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Anand Rathnas
Anand Rathnas

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Stripe Webhooks Return Empty Objects: The API Version Mismatch Fix

#stripe #springboot #webhook #payment

Your Stripe webhook handler suddenly returns null objects. No errors. No warnings. Just... nothing. Here's what's happening and how to fix it.

The Symptom 

Event event = Webhook.constructEvent(payload, signature, webhookSecret);
EventDataObjectDeserializer deserializer = event.getDataObjectDeserializer();

if (deserializer.getObject().isPresent()) {
    // This never executes
    StripeObject stripeObject = deserializer.getObject().get();
}
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The getObject() call returns Optional.empty(). Your webhook receives events, signature validates, but the actual data object is missing.

The Root Cause

Stripe's SDK is strict about API versions. When the event's api_version doesn't match your SDK's version, getObject() silently returns empty.

From Stripe's perspective, this is safety. Different API versions have different object structures. Deserializing a v2023-10-16 object with a v2024-04-10 SDK could break.

But in practice? It usually works fine. And you need that data.

The Fix

Use deserializeUnsafe():

public void handleStripeEvent(Event event) {
    EventDataObjectDeserializer deserializer = event.getDataObjectDeserializer();

    StripeObject stripeObject = null;

    if (deserializer.getObject().isPresent()) {
        stripeObject = deserializer.getObject().get();
    } else {
        // API version mismatch - use unsafe deserialization
        try {
            stripeObject = deserializer.deserializeUnsafe();
            log.debug("Used unsafe deserialization for event: {}", event.getType());
        } catch (Exception e) {
            log.error("Failed to deserialize Stripe event: {}", e.getMessage());
            throw new StripeException("Cannot process webhook event");
        }
    }

    // Now handle your event
    if (stripeObject instanceof Session session) {
        handleCheckoutSession(session);
    }
}
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Why This Happens

  1. Dashboard sends events with its API version - Your Stripe dashboard has an API version setting
  2. SDK has a compiled-in version - The stripe-java JAR knows what version it supports
  3. Mismatch = empty object - Different versions? SDK refuses to deserialize

Check your versions:

# Your SDK version (from pom.xml or build.gradle)
implementation 'com.stripe:stripe-java:26.12.0'

# Dashboard API version
# Dashboard → Developers → API version
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The "Unsafe" Part

The method is called "unsafe" because:

  1. Field mismatches - Renamed/removed fields might cause issues
  2. Type changes - A field that was String might now be an object
  3. Missing data - New required fields won't exist

In practice, for checkout.session.completed, invoice.paid, and common webhook events, deserializeUnsafe() works reliably. The object structures rarely change drastically.

Better Long-Term Fix

Pin your API version to match:

Stripe.apiVersion = "2023-10-16"; // Match your dashboard
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Or upgrade your Stripe dashboard to match your SDK version.

Testing Webhooks Locally

When testing with mock payloads, include the api_version field:

String payload = """
    {
        "id": "evt_test_123",
        "object": "event",
        "type": "checkout.session.completed",
        "api_version": "2023-10-16",
        "created": 1703894400,
        "livemode": false,
        "data": {
            "object": {
                "id": "cs_test_123",
                "object": "checkout.session",
                "customer_email": "test@example.com",
                "status": "complete",
                "payment_status": "paid",
                "metadata": {
                    "tier": "PRO"
                }
            }
        }
    }
    """;
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Missing api_version causes NullPointerException deep in the SDK.

Complete Webhook Handler 

@PostMapping("/webhooks/stripe")
public ResponseEntity<Void> handleStripeWebhook(
        @RequestBody String payload,
        @RequestHeader("Stripe-Signature") String signature) {

    Event event;
    try {
        event = Webhook.constructEvent(payload, signature, webhookSecret);
    } catch (SignatureVerificationException e) {
        return ResponseEntity.badRequest().build();
    }

    EventDataObjectDeserializer deserializer = event.getDataObjectDeserializer();
    StripeObject stripeObject = deserializer.getObject()
            .orElseGet(() -> {
                try {
                    return deserializer.deserializeUnsafe();
                } catch (Exception e) {
                    log.error("Deserialization failed: {}", e.getMessage());
                    return null;
                }
            });

    if (stripeObject == null) {
        return ResponseEntity.status(HttpStatus.UNPROCESSABLE_ENTITY).build();
    }

    switch (event.getType()) {
        case "checkout.session.completed" ->
            handleCheckout((Session) stripeObject);
        case "invoice.paid" ->
            handleInvoicePaid((Invoice) stripeObject);
        case "customer.subscription.deleted" ->
            handleSubscriptionCanceled((Subscription) stripeObject);
    }

    return ResponseEntity.ok().build();
}
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Takeaway

When getObject() returns empty, don't panic. It's likely an API version mismatch. Use deserializeUnsafe() as a fallback, and consider aligning your dashboard and SDK versions for a permanent fix.

Hit this issue before? What's your approach to Stripe webhook versioning?

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Tags: #stripe #java #springboot #webhooks #payments #debugging

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