Ajax client-side framework failed to load Asp.Net 4.0

Question

I got a complicated problem with ASP.Net 4.0 Ajax....I started a website with Visual Studio 2010 on my machine,and added some update panels they used to work fine,but sudden

Answer 1

It may be simply missing part in your web.config like the of , my advice is if you have old copy of your web config try it out.