Unable to get property 'value' in Telerik.Web.UI.RadInputExtender.prototype.isEmpty

Question

I received the following error , it triggered trough Telerik.Web.UI.WebResource.axd during processing submit event, so I don't know which component causes the problem.

In Telerik.Web.UI.WebResource.axd at line 31126

if(!(a.value&&a.value.replace(/ /g,""))){return true;

It gives errors saying:

Unable to get property 'value' of undefined or null reference

​Well I understand the a is null, but to which telerik or ui item is it referring?

The Call Stack is:

Telerik.Web.UI.RadInputExtender.prototype.isEmpty [Line: 31126, Col: 1], Telerik.Web.UI.WebResource.axd
Telerik.Web.UI.RadInputExtender.prototype.get_value [Line: 31132, Col: 7], Telerik.Web.UI.WebResource.axd
Telerik.Web.UI.RadInputExtender.prototype._beforeSubmit [Line: 31248, Col: 1], Telerik.Web.UI.WebResource.axd
Telerik.Web.UI.RadInputManager.prototype._beforeSubmit [Line: 31311, Col: 6], Telerik.Web.UI.WebResource.axd
Telerik.Web.UI.RadInputManager.prototype._onSubmit [Line: 31307, Col: 58], Telerik.Web.UI.WebResource.axd
Telerik.Web.UI.RadInputManager.WebForm_OnSubmit [Line: 31322, Col: 56], Telerik.Web.UI.WebResource.axd
onsubmit [Line: 21, Col: 90], ManualInvoiceEdit2.aspx
Sys.WebForms.PageRequestManager.prototype._onFormSubmit [Line: 15, Col: 22512], Telerik.Web.UI.WebResource.axd
Sys.WebForms.PageRequestManager.prototype._doPostBack [Line: 15, Col: 15349], Telerik.Web.UI.WebResource.axd
Sys.WebForms.PageRequestManager.prototype._doPostBackWithOptions [Line: 15, Col: 16021], Telerik.Web.UI.WebResource.axd
Anonymous function [Line: 6, Col: 298], Telerik.Web.UI.WebResource.axd
Global code [Line: 1, Col: 1], script block (423)

I have

Telerik.Web.UI.dll 2016.2.504.40

Telerik.Web.UI.Skins.dll 2016.2.504.40

jQuery 1.11.1 ​ I have tried in MSIE 9, 10, 11, Firefox and chrome versions published in last 5 years, it always gives the error.

Any help or comment?