title: Why does ODAC Connection.open() sometimes raise an OracleException?
body: <p>I catch an exception with empty message just at <code>Connection.Open()</code> line.</p>
  
  <p>the error code:-2147467259</p>
  
  <p>the stack trace:</p>
  
  <pre><code>at Oracle.DataAccess.Client.OracleException.HandleErrorHelper(Int32 errCode, OracleConnection conn, IntPtr opsErrCtx, OpoSqlValCtx* pOpoSqlValCtx, Object src, String procedure, Boolean bCheck, Int32 isRecoverable)
  at Oracle.DataAccess.Client.OracleException.HandleError(Int32 errCode, OracleConnection conn, IntPtr opsErrCtx, Object src)
  at Oracle.DataAccess.Client.OracleConnection.Open()
  </code></pre>
  
  <p>I say "sometimes" in my question because it really is sometimes. When I remove the <strong>Oracle.DataAccess</strong> reference and again I add it from the installation folder of ODP.net this problem disappeared for a while. But again I catch this awful exception without any clear reason for me.
  What are the reasons behind this problem?</p>