People Editor control is not working properly inside the Update Panel / inside the GridView

Solution: Insert the Script  

<script type="text/javascript" src="/_layouts/15/entityeditor.js"></script> 

Under the Update panel control.. as shown below

<asp:UpdatePanel ID="UpdatePanel1" RenderMode="Inline" runat="server">

  <ContentTemplate>

      <script type="text/javascript" src="/_layouts/15/entityeditor.js"></script>

        <%--Page Or Layoutview Right Side Quick launch--%>

        <div id="divRightView" class="w3-col l9 w3-padding-ver-16" style="width: 80%">

       <asp:GridView ID="gvFilesView" runat="server" ShowHeaderWhenEmpty="True….

       .....

       .....

 <SharePoint:PeopleEditor ID="ppeSelectForViewer" runat="server" MaximumHeight="200" Width="95%" Style="padding: 1px;" BorderColor="#e8e8e8" BorderWidth="1px" BorderStyle="Solid" MaximumEntities="3" ToolTip="Type/Select User name and click on Add User." MultiSelect="true" ValidatorEnabled="true"  Height="90%"> </SharePoint:PeopleEditor>

.....

....

</div>