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