Receive error message Pre-request Script ... (reading 'lengt

Hi all,

Apologies I’m very new to postman. This is either a bug or i’m missing something very obvious.

I use a curl command on linux to remotely get instance status and to start and stop an oracle cloud (oci) instance (VM).

I am trying to do the same using postman.

I have followed the instructions on the below link
Invoking Oracle OCI REST APIs using Postman to Start/Stop the instance as well as many many other websites.

While I can Get instance information proving that the authentication is working correctly when I try and send POST request to start and stop the instance I get the below error message.

There was an error in evaluating the Pre-request Script:TypeError: Cannot read properties of undefined (reading ‘length’).

The environment settings are the attached, There is a length field which i have tried populating, I have also tried removing it but the error message stays the same

Headers with errrors


Can someone point me in the right direction? I have search postman forums, oracle support website and also google but no luck.




Hey @flight-operator-3342 :wave:

Welcome to the Postman community :postman:

As your request screenshot doesn’t show anything in the pre-request script, I can only assume that it’s something at the Collection level.

If you click on the Collection name in the breadcrumb above the URL bar. That should open the Collection in a new tab.

Does that contain anything in the pre-request tab?

Hi Danny,

There was an entry in the Pre-request Script of the parent collection.

I changed

var body = "";

if(methodsThatRequireExtraHeaders.indexOf(request.method.toUpperCase()) !== -1) {
    body = pm.request.body.raw;
    //pm.environment.set("length", body.length);
   var content_length_header = "content-length: "+ body.length ;


var body = "";

if (methodsThatRequireExtraHeaders.indexOf(request.method.toUpperCase()) !== -1) {
    if (pm.request.body && pm.request.body.raw) {
        body = pm.request.body.raw;
var content_length_header = "content-length: " + body.length;

And now the start and stop works correctly.

I am unsure how this worked for other people but with the update it now works for me.



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