After running the SIF for sitecore 9 while browsing the website got the error HTTP 500.19 Errors
Config Error This configuration section cannot be used at this path. This happens when the section is locked at a parent level. Locking is either by default (overrideModeDefault=”Deny”), or set explicitly by a location tag with overrideMode=”Deny” or the legacy allowOverride=”false”.
Config File \\?\C:\inetpub\wwwroot\Webiste\web.config
After a bit of research I found that Application Development feature is not installed.
So followed below steps to enable it.
Go to Start ->control Panel -> Programs and Features -> Turn Windows Features on or off then selected as below.
After installing it the site worked!!!