Hi,
Is there an easy way (interface, wizard.....) to have my old web apps (currently using telerik old ASP.NET) upgraded to the current ASP.NET AJAX version? Or i have to go to each page and manually change the source codes?
Unfortunately I don't think there is a nice and easy wizard/converter or something like that. What is available though is documentation articles like this one. I believe each control has a section like this which will help you transfer from an ASP.NET application to an ASP.NET Ajax application on a control-by-control basis. Hopefully this helps!