Here is a code sample of my test page.
<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="junk2.aspx.cs" Inherits="Testing.junk2" %><%@ Register Assembly="Telerik.Web.UI" Namespace="Telerik.Web.UI" TagPrefix="telerik" %><%--<%@ Register Src="~/CustomControls/Header.ascx" TagPrefix="uc1" TagName="Header" %>--%><!DOCTYPE html><html xmlns="http://www.w3.org/1999/xhtml"><head runat="server"> <title></title></head><body> <form id="form1" runat="server"> <div> <telerik:RadScriptManager runat="server" ID="rsm"> </telerik:RadScriptManager> <telerik:RadTextBox runat="server" ID="txtFriendly" Width="400px" Skin="Silk"></telerik:RadTextBox> <asp:RequiredFieldValidator runat="server" ID="RequiredFieldValidator1" ControlToValidate="txtFriendly" Display="Dynamic" ErrorMessage=" * required" CssClass=" text-danger"/> <telerik:RadTextBox runat="server" ID="txtSubject" Width="400px" Skin="Silk" ></telerik:RadTextBox> <%-- <asp:RequiredFieldValidator runat="server" ID="RequiredFieldValidator5" ControlToValidate="txtSubject" Display="Dynamic" ErrorMessage=" * required" CssClass=" text-danger"/> --%> <telerik:RadWindowManager ID="RadWindowManager1" runat="server"> </telerik:RadWindowManager> <asp:Button runat="server" ID="btntest" OnClick="btntest_Click" Text="test" CausesValidation="false" /> </div> </form></body></html>
And the codebehind:
protected void btntest_Click(object sender, EventArgs e) { RadWindow newWindow = new RadWindow(); newWindow.NavigateUrl = "http://www.google.com"; newWindow.VisibleOnPageLoad = true; RadWindowManager1.Windows.Add(newWindow); }
If I comment out either (or both) of the 2 RequiredFieldValidator's, the modal displays. It doesn't matter which one is commented.
If both are on the page, I get no modal dialog.
We are using v2016.3.1018.45