To get the SphinxSearch plugin working under Vanilla 2.6, you need to change a couple of lines of code.
In the plugin, find all instances of Gdn::Session()->GetPermissions(); and replace with Gdn::Session()->getPermissionsArray();
@jamesinc Hi, thanks for the suggestion. I haven't been active on these forums in a while. Can you please initiate a pull request with your changes? https://github.com/bauerjj/SphinxSearchPlugin
@jamesinc I updated the plugin for 2.6 compatibility finally on github. The next task will be replicating the advanced search dropdown menu like what is shown here on the official Vanilla Forums.