Resolving Stripe Webhook Signature Verification Error

stripe webhooks next.js vercel

A step-by-step guide to identifying and resolving the Stripe webhook signature verification error caused by an extra newline character in the environment variable.

Introduction

This document provides a comprehensive guide on resolving the Stripe webhook signature verification error that occurred in a Next.js project deployed on Vercel, using Caddy for reverse proxy. The error was due to an extra newline character in the STRIPE_WEBHOOK_SECRET environment variable. By following this guide, you can troubleshoot similar issues and ensure smooth operation of your Stripe webhooks.

Problem Description

The application encountered an error with Stripe webhook integration where the signature verification was failing. The specific error message indicated:

Webhook Error: No signatures found matching the expected signature for payload. Are you passing the raw request body you received from Stripe? If a webhook request is being forwarded by a third-party tool, ensure that the exact request body, including JSON formatting and new line style, is preserved.
Note: The provided signing secret contains whitespace. This often indicates an extra newline or space is in the value.

Root Cause

Upon investigation, it was discovered that the STRIPE_WEBHOOK_SECRET environment variable in Vercel had an extra newline character at the end. This extra character caused the signature verification to fail as it did not match the expected signature format.

Solution

Step 1: Identify the Extra Character

  1. Check Environment Variable: Inspect the STRIPE_WEBHOOK_SECRET environment variable in Vercel's dashboard.
  2. Remove Whitespace: Ensure that there are no extra spaces or newline characters at the end of the secret.

Step 2: Update Environment Variable in Vercel

  1. Navigate to Environment Variables:

    • Go to your project in the Vercel dashboard.
    • Click on the "Settings" tab.
    • Scroll down to "Environment Variables".

  2. Edit the Variable:

    • Locate the STRIPE_WEBHOOK_SECRET variable.
    • Remove any extra whitespace or newline characters.
    • Save the changes.

Step 3: Redeploy

  1. Restart Services:
    • After updating the environment variable, redeploy your application to apply the changes.

Conclusion

By ensuring the STRIPE_WEBHOOK_SECRET does not contain any extra whitespace or newline characters and properly handling the raw request body, the Stripe webhook signature verification error was resolved. This guide provides a detailed approach to identifying and fixing such issues, ensuring reliable and secure webhook integration.