Stripe webhook returning 308 error when calling Vercel serverless function

I've set up a webhook with Stripe, which calls a serverless function when it's triggered.

The function is intended to update an entry in my database when it's called, suggesting that a user has signed up for a premium account.

When I run this locally, the webhook works perfectly. It triggers the API, updates the user and processes the payment.

However, when it gets run on live, I continually get a 308 error saying:

> Redirecting to my-app-url.com

Here's the code for my function:

import { buffer } from "micro"
import { createClient } from "@supabase/supabase-js";

require("dotenv").config();

const stripe = require("stripe")(process.env.STRIPE_LIVE_KEY)

const endpointSecret = process.env.STRIPE_WEBHOOK_SECRET

const supabaseUrl = process.env.REACT_APP_SUPABASE_URL
const supabaseAnonKey = process.env.REACT_APP_SUPABASE_ANON_KEY

const supabase = createClient(supabaseUrl, supabaseAnonKey)

module.exports = async (req, res) => {

   const signature = req.headers["stripe-signature"]
   const reqBuffer = await buffer(req)

   let event 

   try {
    event = stripe.webhooks.constructEvent(reqBuffer, signature, endpointSecret)
   } catch (err) {
    console.log(err)
    return res.status(400).send(`Webhook error: ${err.message}`)
   }

   if (event.type === "checkout.session.completed") {
    console.log("Checkout completed!")
    const userId = String(event.data.object.client_reference_id)

    console.log(userId)

    const { error } = await supabase.from('profiles').update({ premium: 'true' }).eq('id', userId) 
    
    if (error) {
      console.log(error)
    }
   }

   res.send({ received: true })
}

When I check my function logs, it just seems like it's not even firing / reaching my API at all - there's no logs.

Does anyone have any suggestions?

The problem is the default domain redirect in Vercel.

The recommended way is to redirect to www, so this is the format you should use:

Wrong: https://[YOUR_DOMAIN].com/api/endpoint

Right: https://www.[YOUR_DOMAIN].com/api/endpoint

Cheers

For my case, it turns out I forgot the trailing slash.

So instead of calling the stripe listener like this:

stripe listen --forward-to localhost:4242/webhook/

I was calling it like this:

stripe listen --forward-to localhost:4242/webhook

Without the / at the end, causing the server to redirect the request to the correct path, and thus the 308 status code.

As the 308 error indicates, it looks like your server is receiving the webhook, but attempting to redirect it to another URL. It's possible that it's even the same URL, but over HTTPS.

Stripe can't follow redirects so this is a misconfiguration on your server's end. You have to give the exact URL for where your server expects to receive webhooks.