Hmmmmm....

[Deleted user]

This is my problem:
I need you to update to +1.17.1+
[14:08:00 ERROR]: null
org.bukkit.command.CommandException: Unhandled exception executing command 'generators' in plugin Generators v1.0
at org.bukkit.command.PluginCommand.execute(PluginCommand.java:47) ~[patched_1.17.1.jar:git-Paper-400]
at org.bukkit.command.SimpleCommandMap.dispatch(SimpleCommandMap.java:159) ~[patched_1.17.1.jar:git-Paper-400]
at org.bukkit.craftbukkit.v1_17_R1.CraftServer.dispatchCommand(CraftServer.java:869) ~[patched_1.17.1.jar:git-Paper-400]
at net.minecraft.server.network.ServerGamePacketListenerImpl.handleCommand(ServerGamePacketListenerImpl.java:2262) ~[app:?]
at net.minecraft.server.network.ServerGamePacketListenerImpl.handleChat(ServerGamePacketListenerImpl.java:2073) ~[app:?]
at net.minecraft.server.network.ServerGamePacketListenerImpl.handleChat(ServerGamePacketListenerImpl.java:2054) ~[app:?]
at net.minecraft.network.protocol.game.ServerboundChatPacket.handle(ServerboundChatPacket.java:46) ~[app:?]
at net.minecraft.network.protocol.game.ServerboundChatPacket.a(ServerboundChatPacket.java:6) ~[app:?]
at net.minecraft.network.protocol.PacketUtils.lambda$ensureRunningOnSameThread$1(PacketUtils.java:56) ~[app:?]
at net.minecraft.server.TickTask.run(TickTask.java:18) ~[patched_1.17.1.jar:git-Paper-400]
at net.minecraft.util.thread.BlockableEventLoop.doRunTask(BlockableEventLoop.java:149) ~[app:?]
at net.minecraft.util.thread.ReentrantBlockableEventLoop.doRunTask(ReentrantBlockableEventLoop.java:23) ~[app:?]
at net.minecraft.server.MinecraftServer.doRunTask(MinecraftServer.java:1426) ~[patched_1.17.1.jar:git-Paper-400]
at net.minecraft.server.MinecraftServer.executeTask(MinecraftServer.java:192) ~[patched_1.17.1.jar:git-Paper-400]
at net.minecraft.util.thread.BlockableEventLoop.pollTask(BlockableEventLoop.java:122) ~[app:?]
at net.minecraft.server.MinecraftServer.pollTaskInternal(MinecraftServer.java:1404) ~[patched_1.17.1.jar:git-Paper-400]
at net.minecraft.server.MinecraftServer.pollTask(MinecraftServer.java:1397) ~[patched_1.17.1.jar:git-Paper-400]
at net.minecraft.util.thread.BlockableEventLoop.managedBlock(BlockableEventLoop.java:132) ~[app:?]
at net.minecraft.server.MinecraftServer.waitUntilNextTick(MinecraftServer.java:1375) ~[patched_1.17.1.jar:git-Paper-400]
at net.minecraft.server.MinecraftServer.runServer(MinecraftServer.java:1286) ~[patched_1.17.1.jar:git-Paper-400]
at net.minecraft.server.MinecraftServer.lambda$spin$0(MinecraftServer.java:319) ~[patched_1.17.1.jar:git-Paper-400]
at java.lang.Thread.run(Thread.java:833) ~[?:?]
Caused by: java.lang.NoSuchMethodError: 'java.lang.String org.bukkit.inventory.Inventory.getTitle()'
at keithcod.es.gui.GUIWindow.show(GUIWindow.java:46) ~[Generators-1.0.jar:?]
at keithcod.es.generators.GUI.ShowInitialGUI(GUI.java:85) ~[Generators-1.0.jar:?]
at keithcod.es.generators.GUI.ShowGUI(GUI.java:27) ~[Generators-1.0.jar:?]
at keithcod.es.generators.Generators.onCommand(Generators.java:102) ~[Generators-1.0.jar:?]
at org.bukkit.command.PluginCommand.execute(PluginCommand.java:45) ~[patched_1.17.1.jar:git-Paper-400]
... 21 more