After doing the update try to click on the update window again. It does not work anymore, so I guess this is the last RoF update.
Before updating, thanks to SteveF btw, make a backup from:
For general settings GFX network, logging etc backup...Rise of Flight\data\startup.cfg
For stick mappings and curves backup this folder...Rise of Flight\data\input
For cockpit views and head position backup this folder...Rise of Flight\data\LuaScripts\snapviews