Top "Webforms" questions

Web Forms is a part of the ASP.

Element <element> is not a known element warning in Visual Studio when using User controls

I have a Visual Studio 2008 project that is showing the following warning when using User Controls, and I haven’t …

asp.net visual-studio webforms user-controls warnings
Calling a 'WebMethod' with jQuery in ASP.NET WebForms

I've set a breakpoint in the following WebMethod but I'm never hitting the breakpoint. cs: [WebMethod] public static string search() { …

jquery asp.net ajax webforms webmethod
If statements in aspx files

I have some code that essentially looks like this: <div> <% if(Something) { %> <div id="someUniqueMarkup"&…

c# asp.net webforms
preventing cross-site request forgery (csrf) attacks in asp.net web forms

I have created an ASP.Net Web Forms application using Visual Studio 2013 and I am using .NET Framework 4.5. I want …

asp.net webforms csrf .net-framework-version
Getting all selected values from an ASP ListBox

I have an ASP ListBox that has the SelectionMode set to "Multiple". Is there any way of retreiving ALL selected …

c# asp.net webforms listbox
Excel spreadsheet generation results in "different file format than extension error" when opening in excel 2007

The spreadsheet still displays, but with the warning message. The problem seems to occur because Excel 2007 is more picky about …

c# excel webforms xls
How to include a partial view inside a webform

Some site I'm programming is using both ASP.NET MVC and WebForms. I have a partial view and I want …

asp.net asp.net-mvc webforms partial-views
Form Elements in ASP.NET Master Pages and Content Pages

OK, another road bump in my current project. I have never had form elements in both my master and content …

asp.net forms webforms master-pages
DropDownList AppendDataBoundItems (first item to be blank and no duplicates)

I have a DropDownList inside an UpdatePanel that is populated on postback from a SqlDataSource. It has a parameter which …

c# asp.net drop-down-menu webforms append
JavaScript getElementById for ASP.NET Control returns null?

I use JavaScript and this error appears for me during execution: Microsoft JScript runtime error: 'document.getElementById(...)' is null …

javascript asp.net webforms getelementbyid