How to Debug and Fix Webhook 400 Bad Request Errors in Your Integration

Webhook 400 Bad Request errors are among the most frustrating integration failures because HTTP 400 gives no clear reason for rejection, leaving developers guessing. The error can stem from several causes including raw body parsing issues, header mismatches, JSON encoding problems, or incorrect middleware order. One of the most common culprits is JSON middleware parsing the request body before signature verification occurs, which destroys the raw bytes needed by providers like Stripe or GitHub. Developers are advised to first capture the exact incoming payload using tools like curl, Postman, or a local webhook inspector before attempting any fix. Properly handling raw body extraction and matching the provider's expected Content-Type are key steps toward resolving these errors reliably.