<configuration>
    <system.web>
        <pages renderAllHiddenFieldsAtTopOfForm="true"></pages>
    </system.web>
</configuration>

<appSettings>
   <add key="ValidationSettings:UnobtrusiveValidationMode" value="None" />
...
</appSettings>
<system.web>
   <machineKey compatibilityMode="Framework45" decryptionKey="somekey" validationKey="otherkey" validation="SHA1" decryption="AES />
   <pages [...] controlRenderingCompatibilityVersion="4.0" enableEventValidation="true" renderAllHiddenFieldsAtTopOfForm="true" />
   <httpRuntime [...] requestValidationMode="2.0" targetFramework="4.5" />
...
</system.web>