Whenever i try to join my server it just dosent let me join it because it just says this:   CClassResolver.java:46) ~ [?:?] at org.inventivetalent.reflection.minecraft.Minecraft.<clinit>(Minecraft.java:62) ~ [?:?] at org.inventivetalent.bossbar.BossBarAPI.<clinit>(BossBarAPI.java:59) ~ [?:?] at org.inventivetalent.bossbar.BossBarPlugin.<init>(BossBarPlugin.java:38) ~ [?:?] at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) ~ [?:1.8.0_121] at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62) ~ [?:1.8.0_121] at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45) ~ [?:1.8.0_121] at java.lang.reflect.Constructor.newInstance(Constructor.java:423) ~ [?:1.8.0_121] at java.lang.Class.newInstance(Class.java:442) ~ [?:1.8.0_121] at org.bukkit.plugin.java.PluginClassLoader.<init>(PluginClassLoader.java:90) ~ [spigot-1.12.2-R0.1-SNAPSHOT-b1638.jar:git-Spigot-2086bb0-8cc5a7e] at org.bukkit.plugin.java.JavaPluginLoader.loadPlugin(JavaPluginLoader.java:129) ~ [spigot-1.12.2-R0.1-SNAPSHOT-b1638.jar:git-Spigot-2086bb0-8cc5a7e] ... 6 more [17:36:20 INFO] : Please contact BlackSpigotMC. 0x0 [17:36:20 INFO] : Stopping server >  But when it says Please contact BlackSpigotMC. 0x0 I don't know what they mean so please can someone help