‘Sys is undefined’ Error in .NET 2.0 and AJAX 1.0 Extensions

If you’re using ASP.NET 2.0 and try to use ajax, you may experience the error ‘Sys is undefined’. If this is the case for you, you’re most likely just missing some configurtion settings in your web.config. To fix your web application, just copy and paste the web.config settings that are missing in your app’s web.config file from the web.config file that’s in ASP.NET Extensions directory (mine is C:\Program Files (x86)\Microsoft ASP.NET\ASP.NET 2.0 AJAX Extensions\v1.0.61025).

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