ERR_INVALID_ARG_TYPE in Node.js — What It Means and How to Fix It

What the Node.js/npm error ERR_INVALID_ARG_TYPE means and how to resolve it.

Published October 25, 2026

ERR_INVALID_ARG_TYPE means a Node.js built-in function received an argument of the wrong type.

Key points

  • Check the exact function signature in the Node.js docs — a common cause is passing a string where a Buffer (or vice versa) is expected
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