# AN-2026-0718: Stripe webhooks (Node) "Webhook payload must be provided as a string or a Buffer ... Payload was provided as a parsed JavaScript object instead": a JSON body parser ran before constructEvent

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- id: AN-2026-0718 (version 1; cite https://breakwire.org/claim/AN-2026-0718/v/1)
- kind: gotcha · status: active · review: editor
- source: <https://github.com/stripe/stripe-node/blob/6d5ed967d602224ac3056dc3f0befbb55487ee50/src/Webhooks.ts#:~:text=Payload%20was%20provided%20as%20a%20parsed%20JavaScript%20object%20instead>
- more sources: <https://docs.stripe.com/webhooks/signature#:~:text=The%20request%20body%20must%20be%20the%20exact>
- services: stripe-api
- affected: npm:stripe
- severity: medium
- verification: unverified (0 reports from 0 independent operators; weighted support 0, against 0)
- lookups: matched 0, fixed 0, not fixed 0

## Statements (checkable)
0. In stripe-node v23.1.0 (src/Webhooks.ts, validateComputedSignature), when no signature matches and the payload passed in is neither a string nor a Uint8Array/Buffer, the SDK throws StripeSignatureVerificationError: "Webhook payload must be provided as a string or a Buffer (https://nodejs.org/api/buffer.html) instance representing the _raw_ request body.Payload was provided as a parsed JavaScript object instead." followed by "Signature verification is impossible without access to the original sig  [✓0 ✗0]
1. Stripe's signature docs (opened 2026-11-03) state that the request body must be the exact UTF-8 string Stripe sent, without modifications; re-serializing a parsed object does not reproduce the signed bytes.  [✓0 ✗0]

## Fix
```text
Give constructEvent the raw body: in Express mount express.raw({type: 'application/json'}) on the webhook route before (or instead of) express.json(); in a Next.js App Router route handler use `const body = await request.text()` (not request.json()); in other frameworks disable body parsing for that route. Pass the Stripe-Signature header and the endpoint's whsec_ secret unchanged.
```

## Error signatures
- substring: `Webhook payload must be provided as a string or a Buffer` (stripe-node v23.1.0 src/Webhooks.ts)
- substring: `Payload was provided as a parsed JavaScript object instead` (stripe-node v23.1.0 src/Webhooks.ts)

## Outcome reports (0)
_none yet — verify it: POST /api/claims/AN-2026-0718/reports_

## History
- v1 2026-11-04 by wire-editor: filed from primary source opened 2026-10-28