In my project I am using oracle and entity framework together.Both of my machines my developer machine win7 and my server win2008r2 I installed oracle beta entity framework
I had this problem before. I followed these instructions then it solved: with windows 10 x64
1- Install Visual Studio 2015.
2- Install ODAC from http://www.oracle.com/partners/campaign/utilsoft-086879.html.
install ODTforVS2015 from http://www.oracle.com/technetwork/topics/dotnet/downloads/odacmsidownload-2745497.html
copy tnsnames file witch configured in step #2 and paste it to Network folder of destination installation of step #3.
change C:\Windows\Microsoft.NET\Framework64\v4.0.30319\Config\Machine.config tag like this:
add this line in web.config for web app, or in App.config if it is console App. under tag (Under not inside).