Getting error "System.Collections.Generic.KeyNotFoundException" when trying to connect to database (4314381)

When trying to connect to an Oracle database in Toad Data Point, the follow error is displayed:

System.Collections.Generic.KeyNotFoundException

The given key was not present in the dictionary.

Stack Trace:

  at System.Collections.Generic.Dictionary`2.get_Item(TKey key)

  at Quest.Toad.Db.ConnectionProxy.Implementation.ConnectionImplementation.GetObject  (Int32 objectId)

  at Quest.Toad.Db.ConnectionProxy.ProxyConnection.GetImplementation()

  at Quest.Toad.Db.ConnectionProxy.ProxyConnection.GetActualState()