It seems the version of the AjaxControlToolkit
is not compatible with System.Web.Extensions
version. Please, check the version of System.Web.Extensions.dll
in the project ~/bin
folder and make sure you use the appropriate AjaxControlToolkit
version. Most probably switching to System.Web.Extensions
version 18.104.22.168 will solve the issue.
Do let us know how it goes.
the Telerik team
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