I created a simple POST request to https://postman-echo.com/post that got a 200 response in both Postman MacOS desktop app and with postman collection run. But newman run returned 400 Bad Request.
After more than an hour of debugging, I found it’s caused by disabling the host system header. Once I enabled that header, newman run succeeded. I’m not sure if this discrepancy in behavior between the Postman tools and newman is expected or a bug, but here’s the minimal repro and fix.
Here’s my exported collection with a single test.
{
"info": {
"_postman_id": "04475dd4-7885-4a87-82db-f74c52708f5a",
"name": "test",
"schema": "https://schema.getpostman.com/json/collection/v2.1.0/collection.json",
"_exporter_id": "44114086",
"_collection_link": "https://dx-6430928.postman.co/workspace/DX's-Workspace~e5abf3c7-74fb-4f68-8a6f-6bfdd3d8c17b/collection/44114086-04475dd4-7885-4a87-82db-f74c52708f5a?action=share&source=collection_link&creator=44114086"
},
"item": [
{
"name": "postman-echo",
"event": [
{
"listen": "test",
"script": {
"exec": [
"pm.test(\"Status code is 200\", function () {",
" console.log(pm.request.headers);",
" pm.response.to.have.status(200);",
"});"
],
"type": "text/javascript",
"packages": {}
}
}
],
"protocolProfileBehavior": {
"protocolVersion": "auto",
"disableCookies": true,
"disabledSystemHeaders": {
"content-length": true,
"host": true,
"user-agent": true,
"accept": true,
"accept-encoding": true,
"connection": true
}
},
"request": {
"method": "POST",
"header": [
{
"key": "Accept",
"value": "application/json",
"type": "text"
}
],
"body": {
"mode": "raw",
"raw": "{\n \"DEAD\": \"BEEF\"\n}",
"options": {
"raw": {
"language": "json"
}
}
},
"url": {
"raw": "https://postman-echo.com/post",
"protocol": "https",
"host": [
"postman-echo",
"com"
],
"path": [
"post"
]
}
},
"response": []
}
]
}
postman collection run succeeds.
$ postman collection run test.postman_collection.json --verbose
No authorization data found. Please use the `postman login` command.
Refer: https://learning.postman.com/docs/postman-cli/postman-cli-options/#postman-login
Running your collection...
postman
test
→ postman-echo
POST https://postman-echo.com/post
200 OK ★ 468 ms time ★ 181 B↑ 925 B↓ size ★ 4↑ 7↓ headers ★ 0 cookies
┌ ↑ raw ★ 22 B
│ {
│ "DEAD": "BEEF"
│ }
└
┌ ↓ application/json ★ text ★ json ★ utf8 ★ 607 B
│ {
│ "args": {},
│ "data": {
│ "DEAD": "BEEF"
│ },
│ "files": {},
│ "form": {},
│ "headers": {
│ "host": "postman-echo.com",
│ "x-request-start": "t1744806655.584",
│ "connection": "close",
│ "content-length": "22",
│ "x-forwarded-proto": "https",
│ "x-forwarded-port": "443",
│ "x-amzn-trace-id": "Root=1-67ffa2ff-29812f605cadb24f479a4c19",
│ "accept": "application/json",
│ "content-type": "application/json",
│ "cache-control": "no-cache",
│ "postman-token": "207c8339-d80b-4d20-9124-03631d81063f"
│ },
│ "json": {
│ "DEAD": "BEEF"
│ },
│ "url": "https://postman-echo.com/post"
│ }
└
prepare wait dns-lookup tcp-handshake ssl-handshake transfer-start download process total
2 ms 5 ms 124 ms 25 ms 56 ms 237 ms 18 ms 277 µs 470 ms
┌
│ [
│ { key: 'Accept', value: 'application/json' },
│ { key: 'Content-Type', value: 'application/json', system: true },
│ { key: 'Cache-Control', value: 'no-cache', system: true },
│ { key: 'Postman-Token', value: '207c8339-d80b-4d20-9124-03631d81063f', system: true }
│ ]
└
✓ Status code is 200
┌─────────────────────────┬───────────────────────┬──────────────────────┐
│ │ executed │ failed │
├─────────────────────────┼───────────────────────┼──────────────────────┤
│ iterations │ 1 │ 0 │
├─────────────────────────┼───────────────────────┼──────────────────────┤
│ requests │ 1 │ 0 │
├─────────────────────────┼───────────────────────┼──────────────────────┤
│ test-scripts │ 1 │ 0 │
├─────────────────────────┼───────────────────────┼──────────────────────┤
│ prerequest-scripts │ 0 │ 0 │
├─────────────────────────┼───────────────────────┼──────────────────────┤
│ assertions │ 1 │ 0 │
├─────────────────────────┴───────────────────────┴──────────────────────┤
│ total run duration: 505 ms │
├────────────────────────────────────────────────────────────────────────┤
│ total data received: 607 B (approx) │
├────────────────────────────────────────────────────────────────────────┤
│ average response time: 468 ms [min: 468 ms, max: 468 ms, s.d.: 0 µs] │
├────────────────────────────────────────────────────────────────────────┤
│ average DNS lookup time: 124 ms [min: 124 ms, max: 124 ms, s.d.: 0 µs] │
├────────────────────────────────────────────────────────────────────────┤
│ average first byte time: 237 ms [min: 237 ms, max: 237 ms, s.d.: 0 µs] │
└────────────────────────────────────────────────────────────────────────┘
Postman api key is required for publishing run details to Postman cloud.
Please specify it by using the `postman login` command
But newman run fails with 400 Bad Request.
$ newman run test.postman_collection.json --verbose
newman
test
→ postman-echo
POST https://postman-echo.com/post
400 Bad Request ★ 164ms time ★ 181B↑ 272B↓ size ★ 4↑ 5↓ headers ★ 0 cookies
┌ ↑ raw ★ 22B
│ {
│ "DEAD": "BEEF"
│ }
└
┌ ↓ text/html ★ text ★ html ★ utf8 ★ 122B
│ <html>
│ <head><title>400 Bad Request</title></head>
│ <body>
│ <center><h1>400 Bad Request</h1></center>
│ </body>
│ </html>
└
prepare wait dns-lookup tcp-handshake ssl-handshake transfer-start download process total
1ms 11ms 2ms 26ms 96ms 19ms 6ms 176µs 165ms
┌
│ [
│ { key: 'Accept', value: 'application/json' },
│ { key: 'Content-Type', value: 'application/json', system: true },
│ { key: 'Cache-Control', value: 'no-cache', system: true },
│ { key: 'Postman-Token', value: 'dad6eda7-e8ee-4b39-938c-0cb8f27a541c', system: true }
│ ]
└
1. Status code is 200
┌─────────────────────────┬────────────────────┬───────────────────┐
│ │ executed │ failed │
├─────────────────────────┼────────────────────┼───────────────────┤
│ iterations │ 1 │ 0 │
├─────────────────────────┼────────────────────┼───────────────────┤
│ requests │ 1 │ 0 │
├─────────────────────────┼────────────────────┼───────────────────┤
│ test-scripts │ 1 │ 0 │
├─────────────────────────┼────────────────────┼───────────────────┤
│ prerequest-scripts │ 0 │ 0 │
├─────────────────────────┼────────────────────┼───────────────────┤
│ assertions │ 1 │ 1 │
├─────────────────────────┴────────────────────┴───────────────────┤
│ total run duration: 212ms │
├──────────────────────────────────────────────────────────────────┤
│ total data received: 122B (approx) │
├──────────────────────────────────────────────────────────────────┤
│ average response time: 164ms [min: 164ms, max: 164ms, s.d.: 0µs] │
├──────────────────────────────────────────────────────────────────┤
│ average DNS lookup time: 2ms [min: 2ms, max: 2ms, s.d.: 0µs] │
├──────────────────────────────────────────────────────────────────┤
│ average first byte time: 19ms [min: 19ms, max: 19ms, s.d.: 0µs] │
└──────────────────────────────────────────────────────────────────┘
# failure detail
1. AssertionError Status code is 200
expected response to have status code 200 but got 400
at assertion:0 in test-script
inside "postman-echo"
Once I changed
"disabledSystemHeaders": {
"content-length": true,
"host": true,
to
"disabledSystemHeaders": {
"content-length": true,
"host": false,
or just removed the "host" entry newman worked.
$ newman run test.postman_collection.json --verbose
newman
test
→ postman-echo
POST https://postman-echo.com/post
200 OK ★ 298ms time ★ 205B↑ 869B↓ size ★ 5↑ 7↓ headers ★ 0 cookies
┌ ↑ raw ★ 22B
│ {
│ "DEAD": "BEEF"
│ }
└
┌ ↓ application/json ★ text ★ json ★ utf8 ★ 537B
│ {
│ "args": {},
│ "data": {},
│ "files": {},
│ "form": {},
│ "headers": {
│ "host": "postman-echo.com",
│ "x-request-start": "t1744806797.833",
│ "connection": "close",
│ "x-forwarded-proto": "https",
│ "x-forwarded-port": "443",
│ "x-amzn-trace-id": "Root=1-67ffa38d-3a59066727c96cd9200aae2d",
│ "accept": "application/json",
│ "content-type": "application/json",
│ "cache-control": "no-cache",
│ "postman-token": "a461906c-e93d-4602-9db8-d7e7707d964c"
│ },
│ "json": null,
│ "url": "https://postman-echo.com/post"
│ }
└
prepare wait dns-lookup tcp-handshake ssl-handshake transfer-start download process total
1ms 11ms 126ms 24ms 99ms 26ms 10ms 244µs 299ms
┌
│ [
│ { key: 'Accept', value: 'application/json' },
│ { key: 'Content-Type', value: 'application/json', system: true },
│ { key: 'Cache-Control', value: 'no-cache', system: true },
│ { key: 'Postman-Token', value: 'a461906c-e93d-4602-9db8-d7e7707d964c', system: true },
│ { key: 'Host', value: 'postman-echo.com', system: true }
│ ]
└
✓ Status code is 200
┌─────────────────────────┬─────────────────────┬────────────────────┐
│ │ executed │ failed │
├─────────────────────────┼─────────────────────┼────────────────────┤
│ iterations │ 1 │ 0 │
├─────────────────────────┼─────────────────────┼────────────────────┤
│ requests │ 1 │ 0 │
├─────────────────────────┼─────────────────────┼────────────────────┤
│ test-scripts │ 1 │ 0 │
├─────────────────────────┼─────────────────────┼────────────────────┤
│ prerequest-scripts │ 0 │ 0 │
├─────────────────────────┼─────────────────────┼────────────────────┤
│ assertions │ 1 │ 0 │
├─────────────────────────┴─────────────────────┴────────────────────┤
│ total run duration: 344ms │
├────────────────────────────────────────────────────────────────────┤
│ total data received: 537B (approx) │
├────────────────────────────────────────────────────────────────────┤
│ average response time: 298ms [min: 298ms, max: 298ms, s.d.: 0µs] │
├────────────────────────────────────────────────────────────────────┤
│ average DNS lookup time: 126ms [min: 126ms, max: 126ms, s.d.: 0µs] │
├────────────────────────────────────────────────────────────────────┤
│ average first byte time: 26ms [min: 26ms, max: 26ms, s.d.: 0µs] │
└────────────────────────────────────────────────────────────────────┘
Postman MacOS desktop app version info
Version 11.41.1-250415-1220
UI Version: 11.41.1-ui-250415-1220
Desktop Platform Version: 11.40.5 (11.40.5)
postman CLI version 1.13.1
newman CLI version 6.2.1