I will look into having caches get deleted on both client and server during updates.
After re-installing the game a second time, as well as removing the
appmanifest file made by Steam, it worked.
For non-Steam users they have to delete the entire game folder, and do
a complete reinstall of the game after restarting the computer to make
it work again.
It seems to happen straight after a content update. So I would assume
it has something to do with differences in the caches between client
and server after restart.
But this will certainly be a major issue on release if we have to tell
every single player to completely reinstall the entire game ever update.
Okay, thank you for this!
I will look into having caches get deleted on both client and server during updates.