I think that the "containers" in the stadium rx3 file or so in which the game puts the banner graphics don't have the correct size. At least it looks like that. I have no experience with creating stadiums though, so I might be wrong.
Thanks for converting these stadiums, I've installed the Mercedes-Benz Arena and it works fine.
However, there's a bug with fan banners. They don't seem to fit into the banner containers of the stadium. I don't know if the size of the banner files has changed since FIFA 14, but is there...
I'll do an update either next weekend or the one after. One of them should finally include Gianluigi Donnarumma, since he'll become 17 next Thursday (on which the squads get updated, so I'm not sure whether they'll include him right away or not).
I'm having the same problem as Munross. Something else I've noticed is that the same error appears when I try to click on "Show/Hide" when viewing the face of a player. However, when I turn off "Show team jersey", the error doesn't appear and the face loads normally. I don't know...
7th January 2016 Squad Database:
Also updated the link in the first post. I'll keep js121's link to the 18th December database as well. Let me know if something's wrong.