Unrecognized attribute 'targetFramework'. Note that attribute names are case-sensitive

http://www.codeproject.com/Questions/281518/Unrecognized-attribute-targetFramework-Note-that-a

Check the .NET version of Application pool in IIS. If application pool is running on .NET version 2 and the web.Config file specify .Net version 4, you get this error.
Note this may not be the only cause for your error. But check this.