What is the solution for “The Type or namespace 'AjaxControlToolkit' could not be found…”?


Error 3 The type or namespace name 'AjaxControlToolkit' could not be found in the global namespace (are you missing an assembly reference?) D:\My App\table\PopUpdata.aspx.designer.cs 58 27 table.

I have Declared this javascript but what is the problem.

<%@ Page Title="Show Data From Menu" Language="C#" MasterPageFile="~/Site.Master" AutoEventWireup="true" CodeBehind="PopUpdata.aspx.cs" Inherits="table.PopUpdata" %> <%@ Register Assembly="AjaxControlToolkit" Namespace="AjaxControlToolkit" TagPrefix="asp" %>


Way to reference a dll is:

<ol><li>In Solution Explorer, select the project.</li> <li>On the Project menu, click Add Reference. The Add Reference dialog box opens.</li> <li>Select the tab indicating the type of component you want to reference. (If you don't find your .dll in the list, then go to the browse tab and find it in your directory)</li> </ol>

An <a href="http://msdn.microsoft.com/en-us/library/fwawt96c%28v=vs.110%29.aspx" rel="nofollow">article</a> on <strong>MSDN</strong> to include installed libraries.

an There is <a href="http://www.asp.net/ajaxlibrary/GetFile.aspx?Page=act&File=AddToolbox.gif" rel="nofollow">another way</a> to do it.


To have the needed references for AjaxControlToolkit

<strong>Right Click project/solution > Manage NuGet Packages..>install Ajax control Toolkit.</strong>

This will add needed assemblies to your solution.


I have faced the same issue. I have deleted all the files from the bin folder and then added the files back to the folder. It worked successfully. Hope it resolves your issue.


You're missing an assembly reference. So you need to reference AjaxControlToolkit.dll in your project.


This is general issue of dll

for solving this you must have 3 dll in your Bin folder


2--AjaxControlToolkit.dll.refresh (Refresh file)

3--AjaxControlToolkit (Program Debug database)

<a href="https://i.stack.imgur.com/uetR9.png" rel="nofollow"><img alt="enter image description here" class="b-lazy" data-src="https://i.stack.imgur.com/uetR9.png" data-original="https://i.stack.imgur.com/uetR9.png" src="https://etrip.eimg.top/images/2019/05/07/timg.gif" /></a>

Now just add the AjaxControlToolkit.dll refrence in your application.


  • Git + GitHub + Dropbox
  • PrimeFaces DataTable selection goes null on dialog.show()
  • Is there a generic TableModel we can use in JTables?
  • std::future returned from std::async hangs while going out of scope
  • Definitions of: AnsiString, WideString, String, char[], char*, BSTR,
  • Stop or Detection dll injection loadlibrary
  • Sending Objects over Java Socket really slow
  • how to make all possible power set(or subset) from arrayList objects?
  • Firebase Notification not working in background
  • Overlaying text on video with required angle using FFMPEG
  • Hyperledger fabric's ChannelCreationPolicy
  • imacros: javascript i get www._undefined_.com error
  • Putting multiple films in a circle in Raphael/Joint.js
  • C# mvc3 redirect sitemap.xml to controller action
  • Ellipsis directive with title
  • Google Maps V3 (PHP/MYSQL with custome infobox)
  • How to set http status code when responding to servlet client from Filter class-method in tomcat
  • Saving CLLocation error: Mutating method sent to immutable object
  • Get the UTM tags with Facebook Marketing API
  • Greedy Algorithm in “C”
  • How to search for a method or variable name within android project?
  • Simultaneous animation when entering editing mode of UITableViewCell
  • Django, uWSGI & nginx: Process dies for “no reason”
  • 'url' requires a non-empty first argument. The syntax changed in Django 1.5, see the docs
  • Stacked bar chart with continuous time-axis as x-axis
  • Capture SIGFPE from SIMD instruction
  • Sign a Pdf using custom digital signature in Java
  • Using Service Component Runtime
  • How do I use TagLib-Sharp to write custom (PRIV) ID3 frames?
  • PHP Permalinks.. how to change?
  • media foundation H264 decoder not working properly
  • CAS 4 - Not able to retrieve the LDAP groups after successful authentication
  • Running R's aov() mixed effects model from Python using rpy2
  • Access to a Matlab gui from the web