If you have problems with updating,
eg. from a client of an older season,
or your updater doesn't work for any reason,
thank Slim who wrote this thing:
The old updater doesn't work, you need UpdaterEx.exe which is provided with the client since a long time.
the fastest way to use new updater if you don't have it is:
1) download http://www.fonline.org/updater/UpdaterEx.exe and place it in game directory
2) open FOnline.cfg with notepad and add these two lines at the end, then run updater:
Note: save the edited FOnline.cfg before you run your new updater.