#3000·nock

v14 no longer supports bodies for 204 responses

Author: alxndrsnCreated Aug 6, 2026Updated Aug 6, 2026

Labelsbug

Please avoid duplicates

I checked all open bugs and none of them matched my problem.

Reproducible test case

to be included in issue body

Nock Version

13, 14

Node Version

TypeScript Version

No response

What happened?

This may be reasonable behaviour, but I thought worth calling out in case anyone else is surprised when upgrading from nock v13 to v14.

It looks like in v13, it was possible to include a response body with a 204 ("No Content") response, but in v14 the body is now ignored.

I couldn't find any reference to this change in Issues.

Repro

`demo.js`

javascript

const assert = require('node:assert');
const http = require('node:http');

const nock = require('nock');

nock('http://api.example.com')
    .get('/')
    .reply(204, {});

const req = http.request('http://api.example.com/', res => {
  let body = '';
  res.on('data', data => body += data);
  res.on('end', () => {
    assert.equal(res.statusCode, 204);
    assert.equal(body, '{}');
  });
});
req.end();

nock v13

$ rm yarn.lock; echo '{ "name":"nock-demo" }' >package.json && echo 'nodeLinker: node-modules' >.yarnrc.yml && volta pin node@24 && volta pin yarn@4 && yarn && yarn add nock@13 && node demo.js; echo "demo.js exited with status: $?"
success: pinned [email protected] (with [email protected]) in package.json
success: pinned [email protected] in package.json
➤ YN0000: · Yarn 4.18.0
➤ YN0000: ┌ Resolution step
➤ YN0000: └ Completed
➤ YN0000: ┌ Fetch step
➤ YN0000: └ Completed
➤ YN0000: ┌ Link step
➤ YN0000: └ Completed
➤ YN0000: · Done in 0s 49ms
➤ YN0000: · Yarn 4.18.0
➤ YN0000: ┌ Resolution step
➤ YN0085: │ + nock@npm:13.5.6, debug@npm:4.4.3, json-stringify-safe@npm:5.0.1, ms@npm:2.1.3, propagate@npm:2.0.1
➤ YN0000: └ Completed in 0s 504ms
➤ YN0000: ┌ Fetch step
➤ YN0000: └ Completed
➤ YN0000: ┌ Link step
➤ YN0000: └ Completed
➤ YN0000: · Done in 0s 550ms
demo.js exited with status: 0

nock v14

$ rm yarn.lock; echo '{ "name":"nock-demo" }' >package.json && echo 'nodeLinker: node-modules' >.yarnrc.yml && volta pin node@24 && volta pin yarn@4 && yarn && yarn add nock@14 && node demo.js; echo "demo.js exited with status: $?"
success: pinned [email protected] (with [email protected]) in package.json
success: pinned [email protected] in package.json
➤ YN0000: · Yarn 4.18.0
➤ YN0000: ┌ Resolution step
➤ YN0000: └ Completed
➤ YN0000: ┌ Fetch step
➤ YN0000: └ Completed
➤ YN0000: ┌ Link step
➤ YN0000: └ Completed
➤ YN0000: · Done in 0s 48ms
➤ YN0000: · Yarn 4.18.0
➤ YN0000: ┌ Resolution step
➤ YN0085: │ + nock@npm:14.0.17, @mswjs/interceptors@npm:0.41.9, @open-draft/deferred-promise@npm:2.2.0, @open-draft/logger@npm:0.3.0, and 6 more.
➤ YN0000: └ Completed in 1s 815ms
➤ YN0000: ┌ Fetch step
➤ YN0000: └ Completed
➤ YN0000: ┌ Link step
➤ YN0000: └ Completed
➤ YN0000: · Done in 1s 910ms
node:assert:152
  throw new AssertionError(obj);
  ^

AssertionError [ERR_ASSERTION]: '' == '{}'
    at IncomingMessage.<anonymous> (/home/user/temp/nock-204/demo.js:15:12)
    at IncomingMessage.emit (node:events:521:24)
    at endReadableNT (node:internal/streams/readable:1736:12)
    at process.processTicksAndRejections (node:internal/process/task_queues:90:21) {
  generatedMessage: true,
  code: 'ERR_ASSERTION',
  actual: '',
  expected: '{}',
  operator: '==',
  diff: 'simple'
}

Node.js v24.19.0
demo.js exited with status: 1

Would you be interested in contributing a fix?

Expected

Maybe helpful to either:

restore previous behaviour, or
throw if a body is supplied when calling .reply(204, ...)

Source: nock/nock

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