[19:50:34] [Server thread/WARN]: java.lang.NullPointerException
[19:50:34] [Server thread/WARN]: at net.minecraft.server.v1_9_R1.Village.a(Village.java:394)
[19:50:34] [Server thread/WARN]: at net.minecraft.server.v1_9_R1.PersistentVillage.a(SourceFile:215)
[19:50:34] [Server thread/WARN]: at net.minecraft.server.v1_9_R1.PersistentCollection.get(PersistentCollection.java:50)
[19:50:34] [Server thread/WARN]: at net.minecraft.server.v1_9_R1.WorldServer.b(WorldServer.java:72)
[19:50:34] [Server thread/WARN]: at net.minecraft.server.v1_9_R1.MinecraftServer.a(MinecraftServer.java:268)
[19:50:34] [Server thread/WARN]: at net.minecraft.server.v1_9_R1.DedicatedServer.init(DedicatedServer.java:269)
[19:50:34] [Server thread/WARN]: at net.minecraft.server.v1_9_R1.MinecraftServer.run(MinecraftServer.java:527)
[19:50:34] [Server thread/WARN]: at java.lang.Thread.run(Thread.java:745)
[19:50:34] [Server thread/INFO]: -------- World Settings For [MainLand_nether] --------

NBTExplorer open Village.dat found next data of only one named Features list
Server is an upgrade from 1.8 to 1.9