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A null customer_email does not, by itself, mean a Stripe webhook failed. If the event contains a Checkout Session, the field is nullable and is intended to prefill Checkout with an email your application already knows. First identify the event and object, then check the email field and Customer reference that fit that object and its state.
Why Stripe can send a null email field
customer_email is a prefill value
When creating a Checkout Session, Stripe documents customer_email as a way to provide an email address already known to your business and prefill the hosted Checkout page. It is not a guarantee that this field will be populated in every webhook payload. If the customer enters an email during Checkout, inspect the resulting Session details and, when appropriate, the associated Customer rather than treating the creation-time prefill field as the only place an email can appear. Stripe’s Checkout Sessions API and Session object reference describe these fields.
Session fields depend on lifecycle state
Stripe’s example Checkout Session has status: open, customer_email: null, and customer_details: null. That demonstrates that null values are valid for an open Session; it does not establish that every completed Session has the same field values. Check the Session status before deciding that an email is missing unexpectedly. Stripe’s Session object reference shows the example and field definitions.
The event may not contain a Checkout Session
A Stripe Event has a type and a data.object; the object depends on which event was emitted. Code that assumes every event’s object has Checkout Session fields can read the wrong field or encounter no such field at all. For a Checkout integration, Stripe highlights checkout.session.completed and asynchronous payment outcome events as server-side events to handle. Choose fields only after identifying the event and its object. Stripe’s Events reference describes event data.
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Webhook event data reflects an API version
Stripe renders event data using the API version in effect when the event was created. Most API v1 events include a versioned snapshot of an API object, so a webhook payload can differ from the shape expected by code generated for a newer version. Inspect event.api_version when a field or type does not match your handler’s expectations; changing the current API version does not rewrite an existing event snapshot. See Stripe’s Events reference and Retrieve an event.
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Debug the payload before changing your code
- Record the event identity and shape. Log the event
id,type,api_version, anddata.object.object. Avoid logging payment secrets or unnecessary personal data. - Branch on the actual object type. For a Checkout Session, inspect
customer_email,customer_details, thecustomerreference, and the Session status. These are distinct fields; do not assume the prefill value is the only post-Checkout email location. The Session object reference defines them. - Use the right creation behavior for your flow. If your application already has the email, supply
customer_emailwhen creating the Session to prefill Checkout. If you need a durable Stripe Customer, account for the Checkout mode andcustomer_creationsetting. Stripe says subscription mode and payment mode withcustomer_creation=alwayscreate a Customer unless an existing Customer was supplied; inspect that Customer when appropriate. See Stripe’s guide to payments for existing customers and the Checkout Sessions API. - Fulfill from server-side payment events. Handle Checkout completion and asynchronous payment outcome events appropriate to your payment methods instead of relying only on the customer’s browser redirect. Stripe discusses these events in its hosted Checkout guidance.
- Check the event’s API version against your handler. Compare
event.api_versionwith the version assumed by your webhook code and generated types. Test with a representative event created under the version your endpoint receives; a newer current API response is not necessarily shaped like an older event snapshot. See Stripe’s Events reference. - For other event types, use that event’s object reference. If
data.object.objectis not a Checkout Session, consult the API reference for the actual object and select the relevant field there. The event type is needed to name that field reliably. Stripe’s Events reference explains the event’s object structure.
Which email location should you check?
- Known before Checkout: use
customer_emailat Session creation to prefill the hosted page. - Entered during Checkout: inspect the completed Session’s
customer_detailsand related Customer as applicable; do not infer the result from the prefill field alone. - Customer record needed: check whether your mode and
customer_creationbehavior create a Customer, or whether you supplied an existing one, then inspect that Customer’s email. - Unexpected field shape: verify the object type and
event.api_versionbefore changing the handler’s field mapping.
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