Selected File Removed on validating and change event of Radio button with update panel in ASP.NET

Question

In my ASPX form I have Update Panel and Script Manager too. When I am changing Radio button oncheckedChanged All selected file will be removed from my aspx file as well as when I submit the form if validation occurs then also file will be removed from fileupload controller.

 <div class="form-group">
    <div class="col-xs-12 col-sm-6 col-md-6 col-lg-6">
        <div class="text-success">
            <span><strong>અરજદારનું નામ ચાલે છે કે કેમ? </strong>
                <asp:RadioButton ID="rdBtnYes" runat="server" Text="હા" GroupName="binKhetidetails" AutoPostBack="true" OnCheckedChanged="rdBtnYes_CheckedChanged" />
                <asp:RadioButton ID="rdBtnNo" runat="server" Text="ના" Checked="True" GroupName="binKhetidetails" AutoPostBack="true" OnCheckedChanged="rdBtnNo_CheckedChanged" /></span>
        </div>
    </div>
</div>


<div class="form-group">
    <div class="col-xs-12 col-sm-6 col-md-4 col-lg-4">
        <div class="text-success">
            <strong>File Upload</strong>
        </div>
        <asp:FileUpload ID="FileUpload1" runat="server" accept=".pdf, image/*"></asp:FileUpload>
    </div>
</div>