I'm trying to do a connection on C# with Oracle on Visual Studio 2015, and at first I had this error "could not load file or Assembly Oracle.DataAccess" then I did a lot of stuff to solve it until I found the
"32-bit Oracle Data Access Components (ODAC) with Oracle Developer Tools for Visual Studio" and the problem did not appeared anymore but when I tried to Open the connection it started to appear this problem "ORA-12154 TNS: could not resolve the connect identifier specified"
And I tried adding the ORACLE_HOME to the system environment variables as one forum suggested it, but it didn't worked and now I'm stuck and don't know what to do, I can connect to the database through sqldeveloper, so I think that the listener is fine.
Have you tried adding the Devart Package? You can add a new reference to your Project by right clicking it in the Solution Explorer.
My second guess would be that maybe the .Net Version of your Project differs from your references.
Although this seems not the case, but maybe it will still help: looking up the ORA Error