ASP.NET

I am using ASP.NET MVC and trying to use HTML.RenderAction to render partial View, inside Main View, but getting error as "Child actions are not allowed to perform redirect actions."

Here is my .cshtml code 

 I have make a chart.js in my website to display chart showing demand of a fruit over date range using this script below :

<div class="chart-wrapper" style="height:200px;margin-top:40px;">
    <canvas id="main-chart" class="chart" height="100"></canvas>
</div>
<script src="https://cdnjs.cloudflare.com/ajax/libs/Chart.js/2.4.0/Chart.min.js">
</script>
<script>
    var ctx = document.getElementById("main-chart").getContext('2d');
    var myChart = new Chart(ctx, {
        type: 'line',
        data: {
            labels: ["M", "T", "W", "T", "F", "S", "S", "M"],
            datasets: [{
                label: 'Traffic',
                data: [0, 50, 100, 150, 200, 250, 300, 350],
                backgroundColor: [
                    'rgba(255, 99, 132, 0.2)',
                    'rgba(54, 162, 235, 0.2)',
                    'rgba(255, 206, 86, 0.2)',
                    'rgba(75, 192, 192, 0.2)',
                    'rgba(153, 102, 255, 0.2)',
                    'rgba(255, 159, 64, 0.2)'
                ],
                borderColor: [
                    'rgba(255,99,132,1)',
                    'rgba(54, 162, 235, 1)',
                    'rgba(255, 206, 86, 1)',
                    'rgba(75, 192, 192, 1)',
                    'rgba(153, 102, 255, 1)',
                    'rgba(255, 159, 64, 1)'
                ],
                borderWidth: 1
            }]
        },
        options: {
            scales: {
                yAxes: [{
                    ticks: {
                        beginAtZero: true
                    }
                }]
            }
        }
    });
</script>

...

I am trying to run this code in asp.net MVC

Controller:

Hi, I am trying to load data in Asp.NET MVC using JsonResult as return type to load rows in jQuery datatable server-side processing, but I am getting this error

This request has been blocked because sensitive information could be disclosed to third party web sites when this is used in a GET request. To allow GET requests, set JsonRequestBehavior to AllowGet.]

So why I am getting this issue and how can I resolve it?

Here is my partial C# code

When I am trying to return JSON data to my jQuery Datatable(Ajax based), It is working in some cases, but it is throwing below error in some cases

I am calculating distance between two Latitude and long
one is the current location of the user and another from the database, I want here if the lat-long distance is between 4km then show data

how can I do it using C#?

I was trying to update my .edmx (ADO.NET) file to get updated or you can say newly added columns, but I wasn't able to get it, what is the proper way to update  or refresh the model to get new database table columns, when the database changes.

I do not want the process of deleting the complete Models and again adding them from database.

I have just started using Cloudinary to upload images for my client's project there & I was trying to upload an image using explanation provided here https://cloudinary.com/documentation/dotnet_image_upload but it's not working for me, can you explain a complete example of this? Or any link of tutorial will also help, thanks.