Ajax Smart Part Not working for User controls in Sharepoint 2013

Dec 30, 2016 at 7:05 AM
HI all ,
I am facing a problem with the Ajax smart part in our site. It's a SharePoint 2013 site.
After adding Ajax smart part to a Share point page and when I try to open the tool pane of smart part all the user controls are not getting loaded there. It shows "Could not load Usercontrol_01.ascx " is shown in the drop down for selection.

Please suggest the solution to this issue.

Thanks in Advance :))))