There is a JavaScript error in your browser console. In serviceportal i am getting the error.

[SoumyasreeP]

function onLoad() {

    var parentsysID = g_form.getParameter('sysparm_parent_sys_id');

    var parentTable = g_form.getParameter('sysparm_parent_table');

    if (parentsysID && parentTable == 'incident') {

        var ga = new GlideAjax("SetAffectedUser");

        ga.addParam('sysparm_name', 'getAffectedUser');

        ga.addParam('sysparm_inc_id', parentsysID);

        ga.getXMLAnswer(function(response) {

            if (response) {

                g_form.setValue('requested_for', response);

            }

        });

    }

}

[Tanushree Maiti]

Hi @SoumyasreeP 

Open browser console and copy the error and paste it here.

Google Chrome (recommended browser😞

1. Open the website you want to check for errors.
2. On your keyboard, press Ctrl + Shift + J (Windows) OR Cmd + Option + J (Mac).
3. A panel will appear—this is the Developer Tools. Click on the “Console” tab at the top if it’s not already open.

Microsoft Edge:

1. Visit the website you want to inspect.
2. Press Ctrl + Shift + J (Windows).
3. Click the “Console” tab if it's not already open. 

https://www.youtube.com/watch?v=oby8r4H4Gnk&t=146s

[SoumyasreeP]

I have already tried this after this also i am getting this error

[Tanushree Maiti]

Also share what value you are getting it in response or share the script include.

[SoumyasreeP]

The script include is-

var SetAffectedUser = Class.create();

SetAffectedUser.prototype = Object.extendsObject(AbstractAjaxProcessor, {

    type: 'SetAffectedUser',

    getAffectedUser: function(){

        var incdentID = this.getParameter('sysparm_inc_id');

        var incGR = new GlideRecord('incident');

        if(incGR.get(incdentID)){

            return incGR.u_affected_user.toString();

        }

        return '';

    }

});