[Fixed] Node.JS 18.16.1 -> Fetcherror: Unsafe Legacy Renegotiation – Node.js

The Problem:

When making an API call using node-fetch library in Node.js, you encounter a ‘FetchError: Unsafe Legacy Renegotiation’ error when using Node.js version 18.16.1, while the code works without errors in Node.js version 16. The error is related to SSL renegotiation and affects HTTPS requests. You’re looking to understand why this error occurs only in Node.js version 18 and not in version 16, and if there are any potential drawbacks to using the suggested workaround.

The Solutions:

Solution 1: Use a custom agent

In Node.js 18, the default behavior for TLS connections is to disable legacy renegotiation. This can be overridden by using a custom agent, as shown below:

const crypto = require('crypto');
const { Agent } = require('undici');

fetch(url, {
  // @ts-ignore
  dispatcher: new Agent({
    connect: {
      rejectUnauthorized: false,
      secureOptions: crypto.constants.SSL_OP_LEGACY_SERVER_CONNECT
    }
  })
});

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