my friend and I have made a few maps and we always send them to each other to play on, the other day, he sent me one, and when I tried to make a game on it i got the mesaage about how "original scenery cannot be modified...please reinstall the game" I didnt reeinstall, because all of the original maps and the maps from the mappack on the official website worked. and we both have the same textures and everything. just the originals and mappack. any ideas what happened and how we can fix it?

i had a similar problem with a special scenery. the only thing that helped was to compile the map again on my own pc.