With a friend we tested the 1.10 and we spawn PolarBear and place some Magma Blocks at a moment the serv crash with this error:

[21:09:24] [Server thread/ERROR]: Encountered an unexpected exception
net.minecraft.server.v1_10_R1.ReportedException: Ticking entity
at net.minecraft.server.v1_10_R1.MinecraftServer.D(MinecraftServer.java:815) ~[Spigot-v1_10.jar:git-Spigot-da278d1-a8a4bed]
at net.minecraft.server.v1_10_R1.DedicatedServer.D(DedicatedServer.java:399) ~[Spigot-v1_10.jar:git-Spigot-da278d1-a8a4bed]
at net.minecraft.server.v1_10_R1.MinecraftServer.C(MinecraftServer.java:672) ~[Spigot-v1_10.jar:git-Spigot-da278d1-a8a4bed]
at net.minecraft.server.v1_10_R1.MinecraftServer.run(MinecraftServer.java:571) [Spigot-v1_10.jar:git-Spigot-da278d1-a8a4bed]
at java.lang.Thread.run(Thread.java:745) [?:1.8.0_60]
Caused by: java.lang.IllegalStateException: Unhandled damage of EntityPolarBear['Polar Bear'/278, l='world', x=-28,33, y=61,00, z=7,65] from hotFloor
at org.bukkit.craftbukkit.v1_10_R1.event.CraftEventFactory.handleEntityDamageEvent(CraftEventFactory.java:559) ~[Spigot-v1_10.jar:git-Spigot-da278d1-a8a4bed]
at org.bukkit.craftbukkit.v1_10_R1.event.CraftEventFactory.handleLivingEntityDamageEvent(CraftEventFactory.java:602) ~[Spigot-v1_10.jar:git-Spigot-da278d1-a8a4bed]
at net.minecraft.server.v1_10_R1.EntityLiving.damageEntity0(EntityLiving.java:1238) ~[Spigot-v1_10.jar:git-Spigot-da278d1-a8a4bed]
at net.minecraft.server.v1_10_R1.EntityLiving.damageEntity(EntityLiving.java:834) ~[Spigot-v1_10.jar:git-Spigot-da278d1-a8a4bed]
at net.minecraft.server.v1_10_R1.BlockMagma.stepOn(SourceFile:38) ~[Spigot-v1_10.jar:git-Spigot-da278d1-a8a4bed]
at net.minecraft.server.v1_10_R1.Entity.move(Entity.java:760) ~[Spigot-v1_10.jar:git-Spigot-da278d1-a8a4bed]
at net.minecraft.server.v1_10_R1.EntityLiving.g(EntityLiving.java:1686) ~[Spigot-v1_10.jar:git-Spigot-da278d1-a8a4bed]
at net.minecraft.server.v1_10_R1.EntityLiving.n(EntityLiving.java:1988) ~[Spigot-v1_10.jar:git-Spigot-da278d1-a8a4bed]
at net.minecraft.server.v1_10_R1.EntityInsentient.n(EntityInsentient.java:512) ~[Spigot-v1_10.jar:git-Spigot-da278d1-a8a4bed]
at net.minecraft.server.v1_10_R1.EntityAgeable.n(EntityAgeable.java:150) ~[Spigot-v1_10.jar:git-Spigot-da278d1-a8a4bed]
at net.minecraft.server.v1_10_R1.EntityAnimal.n(EntityAnimal.java:25) ~[Spigot-v1_10.jar:git-Spigot-da278d1-a8a4bed]
at net.minecraft.server.v1_10_R1.EntityLiving.m(EntityLiving.java:1817) ~[Spigot-v1_10.jar:git-Spigot-da278d1-a8a4bed]
at net.minecraft.server.v1_10_R1.EntityInsentient.m(EntityInsentient.java:240) ~[Spigot-v1_10.jar:git-Spigot-da278d1-a8a4bed]
at net.minecraft.server.v1_10_R1.EntityPolarBear.m(SourceFile:146) ~[Spigot-v1_10.jar:git-Spigot-da278d1-a8a4bed]
at net.minecraft.server.v1_10_R1.World.entityJoinedWorld(World.java:1621) ~[Spigot-v1_10.jar:git-Spigot-da278d1-a8a4bed]
at net.minecraft.server.v1_10_R1.World.g(World.java:1596) ~[Spigot-v1_10.jar:git-Spigot-da278d1-a8a4bed]
at net.minecraft.server.v1_10_R1.World.tickEntities(World.java:1430) ~[Spigot-v1_10.jar:git-Spigot-da278d1-a8a4bed]
at net.minecraft.server.v1_10_R1.WorldServer.tickEntities(WorldServer.java:632) ~[Spigot-v1_10.jar:git-Spigot-da278d1-a8a4bed]
at net.minecraft.server.v1_10_R1.MinecraftServer.D(MinecraftServer.java:804) ~[Spigot-v1_10.jar:git-Spigot-da278d1-a8a4bed]
... 4 more
[21:09:24] [Server thread/ERROR]: Cause of unexpected exception was
java.lang.IllegalStateException: Unhandled damage of EntityPolarBear['Polar Bear'/278, l='world', x=-28,33, y=61,00, z=7,65] from hotFloor
at org.bukkit.craftbukkit.v1_10_R1.event.CraftEventFactory.handleEntityDamageEvent(CraftEventFactory.java:559) ~[Spigot-v1_10.jar:git-Spigot-da278d1-a8a4bed]
at org.bukkit.craftbukkit.v1_10_R1.event.CraftEventFactory.handleLivingEntityDamageEvent(CraftEventFactory.java:602) ~[Spigot-v1_10.jar:git-Spigot-da278d1-a8a4bed]
at net.minecraft.server.v1_10_R1.EntityLiving.damageEntity0(EntityLiving.java:1238) ~[Spigot-v1_10.jar:git-Spigot-da278d1-a8a4bed]
at net.minecraft.server.v1_10_R1.EntityLiving.damageEntity(EntityLiving.java:834) ~[Spigot-v1_10.jar:git-Spigot-da278d1-a8a4bed]
at net.minecraft.server.v1_10_R1.BlockMagma.stepOn(SourceFile:38) ~[Spigot-v1_10.jar:git-Spigot-da278d1-a8a4bed]
at net.minecraft.server.v1_10_R1.Entity.move(Entity.java:760) ~[Spigot-v1_10.jar:git-Spigot-da278d1-a8a4bed]
at net.minecraft.server.v1_10_R1.EntityLiving.g(EntityLiving.java:1686) ~[Spigot-v1_10.jar:git-Spigot-da278d1-a8a4bed]
at net.minecraft.server.v1_10_R1.EntityLiving.n(EntityLiving.java:1988) ~[Spigot-v1_10.jar:git-Spigot-da278d1-a8a4bed]
at net.minecraft.server.v1_10_R1.EntityInsentient.n(EntityInsentient.java:512) ~[Spigot-v1_10.jar:git-Spigot-da278d1-a8a4bed]
at net.minecraft.server.v1_10_R1.EntityAgeable.n(EntityAgeable.java:150) ~[Spigot-v1_10.jar:git-Spigot-da278d1-a8a4bed]
at net.minecraft.server.v1_10_R1.EntityAnimal.n(EntityAnimal.java:25) ~[Spigot-v1_10.jar:git-Spigot-da278d1-a8a4bed]
at net.minecraft.server.v1_10_R1.EntityLiving.m(EntityLiving.java:1817) ~[Spigot-v1_10.jar:git-Spigot-da278d1-a8a4bed]
at net.minecraft.server.v1_10_R1.EntityInsentient.m(EntityInsentient.java:240) ~[Spigot-v1_10.jar:git-Spigot-da278d1-a8a4bed]
at net.minecraft.server.v1_10_R1.EntityPolarBear.m(SourceFile:146) ~[Spigot-v1_10.jar:git-Spigot-da278d1-a8a4bed]
at net.minecraft.server.v1_10_R1.World.entityJoinedWorld(World.java:1621) ~[Spigot-v1_10.jar:git-Spigot-da278d1-a8a4bed]
at net.minecraft.server.v1_10_R1.World.g(World.java:1596) ~[Spigot-v1_10.jar:git-Spigot-da278d1-a8a4bed]
at net.minecraft.server.v1_10_R1.World.tickEntities(World.java:1430) ~[Spigot-v1_10.jar:git-Spigot-da278d1-a8a4bed]
at net.minecraft.server.v1_10_R1.WorldServer.tickEntities(WorldServer.java:632) ~[Spigot-v1_10.jar:git-Spigot-da278d1-a8a4bed]
at net.minecraft.server.v1_10_R1.MinecraftServer.D(MinecraftServer.java:804) ~[Spigot-v1_10.jar:git-Spigot-da278d1-a8a4bed]
at net.minecraft.server.v1_10_R1.DedicatedServer.D(DedicatedServer.java:399) ~[Spigot-v1_10.jar:git-Spigot-da278d1-a8a4bed]
at net.minecraft.server.v1_10_R1.MinecraftServer.C(MinecraftServer.java:672) ~[Spigot-v1_10.jar:git-Spigot-da278d1-a8a4bed]
at net.minecraft.server.v1_10_R1.MinecraftServer.run(MinecraftServer.java:571) [Spigot-v1_10.jar:git-Spigot-da278d1-a8a4bed]
at java.lang.Thread.run(Thread.java:745) [?:1.8.0_60]
[21:09:24] [Server thread/ERROR]: This crash report has been saved to: /home/a772014010200104722/27599/./crash-reports/crash-2016-06-10_21.09.24-server.txt
[21:09:24] [Server thread/INFO]: Stopping server

We kill the Polar Bear with MCEdit and it work fine after.