Stripe webhook · server log

Edge runtime / crypto errors

SubtleCryptoProvider cannot be used in a synchronous context. Use `await constructEventAsync(...)` instead of `constructEvent(...)`

What it means

constructEvent is synchronous and uses Node's crypto. On the Edge runtime or Cloudflare Workers only Web Crypto exists, which is async.

Common causes

• export const runtime = "edge" on the webhook route
• Deploying to Cloudflare Workers / Pages
• A bundler polyfill that breaks node:crypto

How to fix it

1. Simplest: export const runtime = "nodejs" on the webhook route
2. On Edge/Workers: await stripe.webhooks.constructEventAsync(body, sig, secret, undefined, Stripe.createSubtleCryptoProvider())
3. Still read the body with await req.text()

const event = await stripe.webhooks.constructEventAsync(
  await req.text(),
  sig,
  process.env.STRIPE_WEBHOOK_SECRET!,
  undefined,
  Stripe.createSubtleCryptoProvider(),
);

$ stripe listen --forward-to localhost:3000/api/stripe/webhook
# put the whsec_... it prints in .env.local, then restart npm run dev
$ stripe trigger checkout.session.completed

Prompt for Cursor or Claude Code

My Stripe webhook throws a crypto/SubtleCryptoProvider error. Check the runtime of src/app/api/stripe/webhook/route.ts. If I'm not deploying to an edge-only platform, set runtime = "nodejs". Otherwise switch to await constructEventAsync with Stripe.createSubtleCryptoProvider().

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