Failed to execute request because the App Domain could not be created
Server Application Unavailable
The web application you are attempting to access on this web server is currently unavailable. Please hit the "Refresh" button in your web browser to retry your request.
Administrator Note: An error message detailing the cause of this specific request failure can be found in the application event log of the web server. Please review this log entry to discover what caused this error to occur.
I have given Read/Write permissions to IIS_WPG and it resolved the problem.
The worker process which is running under user account needs to have read/write access to your root folders and files like web.config.
I added that User account (admin) under IIS_WPG.
How to add those permissions to your web directory
1. Open IIS
2. Right cliek on it and hit permission
3. Find IIS_WPG using advanced search option.
4. check Read/Write check boxes.
5. Now, yuo can browse the web.