: Ensure your project targets .NET Framework 4.0 or higher , as recent versions of the toolkit do not support older frameworks.
Browse to the AjaxControlToolkit.dll to populate the list with controls like CalendarExtender , Accordion , and ModalPopupExtender . ⚠️ Security & Versioning Note Download Ajax Control Toolkit zip
: Remember that most toolkit controls require a ScriptManager or ToolkitScriptManager on the page to function correctly. : Ensure your project targets
: This is the modern standard for adding the toolkit to Visual Studio projects. You can install it via the Package Manager Console: Install-Package AjaxControlToolkit Download Ajax Control Toolkit zip