Error: unable to reflect System.web.configuration.machinekeySection with local iis

I am running an asp.net 3.5 web application with visual studio 2017. Everything working fine when i am running using IIS express but with classic pipeline. But I changed the settings (project properties-->Web-->Servers --> local iis; Created virtual directory as well) to run using local iis it is giving me the error "unable to reflect System.web.configuration.machinekeySection" . I am using IIS 7.5 and windows 7

I tried creating the machine key(both validation and decryption key) in iis but still issue persists.

Do anyone have any idea?? Please help here :)

Attaching the error description image here

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