WebForm_... is not Defined error

If you get this error "WebForm_ is not defined error..."
and previously you never get this problem...

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you may install a plugin which compress the .axd file...

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solution:
you need to exclude them on the compression module...
please check your .axd name.. and exclude them on your HTTP compression module


it needs this 2 file not to be compressed
System.Web.Script.Services.ScriptHandlerFactory, System.Web.Extensions

and

System.Web.Handlers.ScriptResourceHandler, System.Web.Extensions