When Ajax is published to the server, the following error occurs: "Unknown Server tag"

This error was not reported during local testing. When the server is accessed, the "Unknown Server tag" is displayed. Finally, check the error,
Web. config missing
<Add tagprefix = "asp" namespace = "system. Web. UI" assembly = "system. Web. Extensions, version = 1.0.61025.0, culture = neutral, publickeytoken = 31bf3856ad364e35"/>
This sentence. Errors:

<System. Web>
<Pages stylesheettheme = "default">
<Controls>
<Add tagprefix = "asp" namespace = "system. Web. UI" assembly = "system. Web. Extensions, version = 1.0.61025.0, culture = neutral, publickeytoken = 31bf3856ad364e35"/>
</Controls>
</Pages>
<! --
Set compilation DEBUG = "true" to insert debugging
Symbols into the compiled page. Because this
Affects performance, set this value to true only
During development.
-->
<Compilation DEBUG = "true">
<Assemblies>
<Add Assembly = "system. Web. Extensions, version = 1.0.61025.0, culture = neutral, publickeytoken = 31bf3856ad364e35"/>
<Add Assembly = "system. Data. oracleclient, version = 2.0.0.0, culture = neutral, publickeytoken = b77a5c561934e089"/> </assemblies>
</Compilation>
<Httphandlers>
<Remove verb = "*" Path = "*. asmx"/>
<Add verb = "post, get" Path = "ajaxpro/*. ashx" type = "ajaxpro. ajaxhandlerfactory, ajaxpro.2"/>
<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 = "*" Path = "* _ appservice. axd "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>
</System. Web>