Unfortunately, we no longer provide support for 3.4, including upgrades. If you take a look at the following location, there are providers who do provide this as a service, which you can find here
https://invisioncommunity.com/third-party/providers/?csrfKey=7568ff7564506961db68f5f5e0cae392&advanced_search_submitted=1&sortby=primary_id_field&sortdirection=asc&content_field_124[1]=9
It is also worth noting here, we do not support the software running on IIS.