I was playing with my friends a UHC Match when the server crashed. When I re-started the server the plugin sent us to 0.0 and they lost all their stuff (Idk why but I didn't lose my stuff). After all we tried to play again and the server crashed again. It happened two days ago and I didn't look for the error in the console or in the logs. However, today I was looking for a new world to play again and when I closed the server I decided to look into the logs and I found this:
I think the message appeared when the server was in my computer too, but it has never crashed before.
[18:37:14] [Server thread/INFO]: Preparing spawn area: 29%
[18:37:15] [Server thread/INFO]: Preparing spawn area: 69%
[18:37:16] [Server thread/INFO]: Preparing start region for level 2 (Seed: -8540363582195314400)
[18:37:17] [Server thread/INFO]: [WorldBorder] Enabling WorldBorder v1.8.7
[18:37:17] [Server thread/INFO]: [WorldBorder] [CONFIG] Using elliptic/round border, knockback of 3.0 blocks, and timer delay of 5.
[18:37:17] [Server thread/INFO]: [WorldBorder] [CONFIG] Border-checking timed task started.
[18:37:17] [Server thread/INFO]: [WorldBorder] For reference, the main world's spawn location is at X: 104.0 Y: 64.0 Z: 256.0
[18:37:17] [Server thread/INFO]: [SpectatorPlus] Enabling SpectatorPlus v2.0
[18:37:17] [Server thread/ERROR]: Error occurred while enabling SpectatorPlus v2.0 (Is it up to date?)
java.lang.NoSuchMethodError: org.bukkit.Server.getOnlinePlayers()[Lorg/bukkit/entity/Player;
at com.pgcraft.spectatorplus.SpectatorPlus.onEnable(SpectatorPlus.java:128) ~[?:?]
at org.bukkit.plugin.java.JavaPlugin.setEnabled(JavaPlugin.java:271) ~inecraft_server.jar:git-Bukkit-c8ff651]
at org.bukkit.plugin.java.JavaPluginLoader.enablePlugin(JavaPluginLoader.java:329) inecraft_server.jar:git-Bukkit-c8ff651]
at org.bukkit.plugin.SimplePluginManager.enablePlugin(SimplePluginManager.java:404) inecraft_server.jar:git-Bukkit-c8ff651]
at org.bukkit.craftbukkit.v1_11_R1.CraftServer.enablePlugin(CraftServer.java:360) inecraft_server.jar:git-Bukkit-c8ff651]
at org.bukkit.craftbukkit.v1_11_R1.CraftServer.enablePlugins(CraftServer.java:322) inecraft_server.jar:git-Bukkit-c8ff651]
at net.minecraft.server.v1_11_R1.MinecraftServer.t(MinecraftServer.java:411) inecraft_server.jar:git-Bukkit-c8ff651]
at net.minecraft.server.v1_11_R1.MinecraftServer.l(MinecraftServer.java:372) inecraft_server.jar:git-Bukkit-c8ff651]
at net.minecraft.server.v1_11_R1.MinecraftServer.a(MinecraftServer.java:327) inecraft_server.jar:git-Bukkit-c8ff651]
at net.minecraft.server.v1_11_R1.DedicatedServer.init(DedicatedServer.java:244) inecraft_server.jar:git-Bukkit-c8ff651]
at net.minecraft.server.v1_11_R1.MinecraftServer.run(MinecraftServer.java:521) inecraft_server.jar:git-Bukkit-c8ff651]
at java.lang.Thread.run(Thread.java:748) [?:1.8.0_144]
[18:37:17] [Server thread/INFO]: [ChangeSkin] Enabling ChangeSkin v3.0
[18:37:17] [Server thread/WARN]: [ChangeSkin] Cannot check bungeecord support. You use a non-spigot build
[18:37:18] [Server thread/INFO]: HikariPool-1 - Starting...
[18:37:18] [Server thread/INFO]: HikariPool-1 - Start completed.
[18:37:18] [Server thread/INFO]: [UHPlugin] Enabling UHPlugin v1.4
[18:37:20] [Server thread/WARN]: [UHPlugin] Invalid value for configuration field 'map.size' : '4,242.64'.
[18:37:20] [Server thread/WARN]: [UHPlugin] Reason : Invalid integer value
[18:37:20] [Server thread/WARN]: [UHPlugin] Some configuration values are invalid. Please check the configuration file.
[18:37:20] [Server thread/INFO]: [UHPlugin] Successfully hooked into WorldBorder.
[18:37:20] [Server thread/INFO]: [UHPlugin] Successfully hooked into SpectatorPlus.
[18:37:20] [Server thread/WARN]: [UHPlugin] Dynmap is not present, so the integration was disabled.
[18:37:20] [Server thread/INFO]: [UHPlugin] Successfully hooked into ProtocolLib.
[18:37:20] [Server thread/INFO]: [UHPlugin] Using VanillaWorldBorder to set the world border.
[18:37:20] [Server thread/INFO]: [UHPlugin] Ultra Hardcore plugin loaded.
[18:37:20] [Server thread/INFO]: Server permissions file permissions.yml is empty, ignoring it
[18:37:21] [Server thread/INFO]: Done (46.061s)! For help, type "help" or "?"
[18:37:21] [Server thread/INFO]: Starting GS4 status listener
[18:37:21] [Query Listener #1/INFO]: Query running on 0.0.0.0:42621
[18:37:28] [Server thread/WARN]: Can't keep up! Did the system time change, or is the server overloaded? Running 6910ms behind, skipping 138 tick(s)
[18:37:32] [Server thread/INFO]: NachoFonta12[/181.168.23.60:56172] logged in with entity id 2138 at ([world]104.0, 85.0, 256.0)
[18:37:40] [Server thread/INFO]: NachoFonta12 issued server command: /tp 0 100 0
[18:37:40] [Server thread/INFO]: [NachoFonta12: Teleported NachoFonta12 to 0.5, 100.0, 0.5]
[18:37:47] [Server thread/WARN]: Can't keep up! Did the system time change, or is the server overloaded? Running 9151ms behind, skipping 183 tick(s)
[18:38:07] [Server thread/WARN]: Can't keep up! Did the system time change, or is the server overloaded? Running 4163ms behind, skipping 83 tick(s)
[18:39:44] [Server thread/INFO]: NachoFonta12 lost connection: Disconnected
[18:39:44] [Server thread/INFO]: NachoFonta12 left the game
[18:42:22] [Server thread/INFO]: Saving...
[18:42:22] [Server thread/INFO]: Saved the world