Verified Developer Solution • 100% OfflineFix "TypeError: Key must be a buffer"
Troubleshoot HMAC generation crashes in Node.js caused by missing or undefined secret keys.
The Problem (Error Root Cause)Exception
When calling `crypto.createHmac()`, Node.js throws `TypeError: Key must be a buffer`. This happens because the secret key you passed is `undefined`, usually due to a missing environment variable.
Identified via runtime validation & stack traces
The Solution (Step-by-Step Fix)Verified
Ensure your `.env` file is loaded correctly and that the secret key exists before attempting to generate the HMAC.
Deterministic, non-destructive resolution
Code Standard: Bad Pattern vs Verified Fix
Live SyntaxAnti-Pattern vs Verified Fix
1// ❌ Bad: Secret is undefined2const secret = process.env.WEBHOOK_SECRET; // Missing!3crypto.createHmac('sha256', secret);4 5// ✅ Good: Fail fast if missing6if (!process.env.WEBHOOK_SECRET) throw new Error("Missing secret");7crypto.createHmac('sha256', process.env.WEBHOOK_SECRET);Test and resolve this using HMAC Generator
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Frequently Asked Questions
Q:Can the key be a string?
Yes, Node.js accepts strings or Buffers for the key. The error specifically occurs when you pass undefined.
Q:How do I test webhook signatures?
Use our HMAC Generator to manually hash payloads using your secret key.