>.... [09:07:09 WARN]: [StackMob] Task #128 for StackMob v5.1.2 generated an exception
java.lang.NoClassDefFoundError: net/minecraft/server/v1_15_R1/Packet
at uk.antiperson.stackmob.tasks.TagTask.sendPacket(TagTask.java:55) ~[?:?]
at uk.antiperson.stackmob.tasks.TagTask.lambda$run$0(TagTask.java:31) ~[?:?]
at java.util.ArrayList.forEach(ArrayList.java:1257) ~[?:1.8.0_242]
at uk.antiperson.stackmob.tasks.TagTask.run(TagTask.java:31) ~[?:?]
at org.bukkit.craftbukkit.v1_16_R1.scheduler.CraftTask.run(CraftTask.java:99) ~[patched_1.16.1.jar:git-Paper-19]
at org.bukkit.craftbukkit.v1_16_R1.scheduler.CraftScheduler.mainThreadHeartbeat(CraftScheduler.java:468) ~[patched_1.16.1.jar:git-Paper-19]
at net.minecraft.server.v1_16_R1.MinecraftServer.b(MinecraftServer.java:1291) ~[patched_1.16.1.jar:git-Paper-19]
at net.minecraft.server.v1_16_R1.DedicatedServer.b(DedicatedServer.java:377) ~[patched_1.16.1.jar:git-Paper-19]
at net.minecraft.server.v1_16_R1.MinecraftServer.a(MinecraftServer.java:1212) ~[patched_1.16.1.jar:git-Paper-19]
at net.minecraft.server.v1_16_R1.MinecraftServer.v(MinecraftServer.java:1000) ~[patched_1.16.1.jar:git-Paper-19]
at net.minecraft.server.v1_16_R1.MinecraftServer.lambda$a$0(MinecraftServer.java:177) ~[patched_1.16.1.jar:git-Paper-19]
at java.lang.Thread.run(Thread.java:748) [?:1.8.0_242]
Caused by: java.lang.ClassNotFoundException: net.minecraft.server.v1_15_R1.Packet
at org.bukkit.plugin.java.PluginClassLoader.findClass(PluginClassLoader.java:105) ~[patched_1.16.1.jar:git-Paper-19]
at org.bukkit.plugin.java.PluginClassLoader.findClass(PluginClassLoader.java:100) ~[patched_1.16.1.jar:git-Paper-19]
at java.lang.ClassLoader.loadClass(ClassLoader.java:419) ~[?:1.8.0_242]
at java.lang.ClassLoader.loadClass(ClassLoader.java:352) ~[?:1.8.0_242]
... 12 more