Well, this is embarassing. I've inherited a VS2012 asp.net (vb) web app. I wanted to use the ModalPopupExtender control. There was nothing in the toolbox, so I right clicked on the Solution -> Manage NuGet Packages -> Online -> Installed Ajax Control Toolkit.
I then added a tab to the toolbox, called it Ajax Control Toolkit. To this, I right-clicked chose Add Items, I browsed to the bin folder, and selected the AjaxControlToolkit.dll.
I then dropped a ModalPopupExtender in the designer. I added some code and saved it. I wanted to test it and now the website won't build. There are 2 similar errors from 2 other pages regarding the ajaxToolkit, specifically, the errors state: Unknown server tag 'ajaxToolkit:toolkitscriptmanager' . Apparently the ajaxtoolkit was used on a couple of other pages at some time, not by me.
I compared the 2 error causing files between my local folder and the dev folder and they are both identical. So, I'm not missing any reference. I compared web.config files too, and they are identical.
I wouldn't have done the installation if I had seen the AjaxToolkit in the toolbox in the first place. My question is "What can I do to get it to build again"?
Please provide detailed help! Thank you!!!