at the end I have solved the problem by myself, in case someone happens to him, I solved it making copy of the world of the server, later creating a world in single player, to copy the files level.dat together with to the folder dim-1, and to replace those of the world downloaded of the server, I uploaded all this to the server and magically it worked.
I imagine that there was some error in the level.dat but I have not been able to locate it.