If you encounter such problems for the first time, refer to the following link in the web. config file:
<HttpHandlers>
<Remove verb = "*" path = "*. asmx"/>
<Add verb = "*" path = "*. asmx "validate =" false "type =" System. web. script. services. scriptHandlerFactory, System. web. extensions, Version = 1.0.61025.0, Culture = neutral, PublicKeyToken = 31bf3856ad364e35 "/>
<Add verb = "GET, HEAD" path = "ScriptResource. axd "type =" System. web. handlers. scriptResourceHandler, System. web. extensions, Version = 1.0.61025.0, Culture = neutral, PublicKeyToken = 31bf3856ad364e35 "validate =" false "/>
</HttpHandlers>
<HttpModules>
<Add name = "ScriptModule" type = "System. Web. Handlers. ScriptModule, System. Web. Extensions, Version = 1.0.61025.0, Culture = neutral, PublicKeyToken = 31bf3856ad364e35"/>
</HttpModules>
In <system. web> </system. web>, the problem is solved.