Stripe Webhook Signature Verification Failing
Your v0-generated Next.js application receives Stripe webhook events but fails to verify their signatures, returning 400 errors or throwing 'Webhook signature verification failed' exceptions. Payments are processed by Stripe but your application never confirms them, leaving orders in a pending state and customers confused.
Stripe signs every webhook event with a signature derived from the raw request body and your webhook signing secret. If the body is modified in any way before verification (such as being parsed as JSON), or if the signing secret is incorrect, verification fails. This is a critical security feature that prevents attackers from sending fake webhook events to your application.
This is one of the most common Stripe integration issues because Next.js API routes automatically parse the request body as JSON, which modifies the raw body that Stripe's verification expects.
Error Messages You Might See
Common Causes
- Body pre-parsed by Next.js — Next.js API routes parse JSON body automatically, but Stripe verification requires the raw body bytes
- Wrong webhook secret — using the API secret key (sk_...) instead of the webhook signing secret (whsec_...)
- Local vs production secret mismatch — Stripe CLI uses a different signing secret than the dashboard webhook endpoint
- App Router body handling — Next.js App Router route handlers consume the body stream, making it unavailable for Stripe verification
- Middleware modifying request — authentication or logging middleware reading the request body before the webhook handler
How to Fix It
- Disable body parsing — for Pages Router:
export const config = { api: { bodyParser: false } } - Read raw body in App Router — use
const body = await request.text()to get the raw body string before any JSON parsing - Use correct signing secret — get the webhook signing secret (whsec_...) from Stripe Dashboard > Webhooks > your endpoint > Signing secret
- Verify with Stripe SDK — use
stripe.webhooks.constructEvent(body, sig, webhookSecret)with the raw body string - Test with Stripe CLI — run
stripe listen --forward-to localhost:3000/api/webhookand use the provided signing secret for local testing - Return 200 quickly — process webhook asynchronously and return 200 immediately to avoid Stripe retry storms
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Get HelpFrequently Asked Questions
Why does webhook verification fail even with the correct secret?
Most likely the request body was parsed as JSON before verification. Stripe needs the raw body bytes. Disable body parsing with config = { api: { bodyParser: false } }.
Where do I find my webhook signing secret?
Go to Stripe Dashboard > Developers > Webhooks > click your endpoint > Signing secret. It starts with whsec_. Do not use your API key (sk_...).
How do I test webhooks locally?
Install Stripe CLI, run 'stripe listen --forward-to localhost:3000/api/webhook', and use the signing secret it outputs (whsec_...) for local testing.