Duels Error

[21:25:47 ERROR]: null
org.bukkit.command.CommandException: Cannot execute command '1v1' in plugin Duels v3.5.2 - plugin is disabled.
        at org.bukkit.command.PluginCommand.execute(PluginCommand.java:37) ~[paper-api-1.18.1-R0.1-SNAPSHOT.jar:?]
        at org.bukkit.command.SimpleCommandMap.dispatch(SimpleCommandMap.java:159) ~[paper-api-1.18.1-R0.1-SNAPSHOT.jar:?]
        at org.bukkit.craftbukkit.v1_18_R1.CraftServer.dispatchCommand(CraftServer.java:908) ~[paper-1.18.1.jar:git-Paper-216]
        at net.minecraft.server.network.ServerGamePacketListenerImpl.handleCommand(ServerGamePacketListenerImpl.java:2289) ~[?:?]
        at net.minecraft.server.network.ServerGamePacketListenerImpl.handleChat(ServerGamePacketListenerImpl.java:2100) ~[?:?]
        at net.minecraft.server.network.ServerGamePacketListenerImpl.handleChat(ServerGamePacketListenerImpl.java:2081) ~[?:?]
        at net.minecraft.network.protocol.game.ServerboundChatPacket.handle(ServerboundChatPacket.java:46) ~[?:?]
        at net.minecraft.network.protocol.game.ServerboundChatPacket.a(ServerboundChatPacket.java:6) ~[?:?]
        at net.minecraft.network.protocol.PacketUtils.lambda$ensureRunningOnSameThread$1(PacketUtils.java:56) ~[?:?]
        at net.minecraft.server.TickTask.run(TickTask.java:18) ~[paper-1.18.1.jar:git-Paper-216]
        at net.minecraft.util.thread.BlockableEventLoop.doRunTask(BlockableEventLoop.java:149) ~[?:?]
        at net.minecraft.util.thread.ReentrantBlockableEventLoop.doRunTask(ReentrantBlockableEventLoop.java:23) ~[?:?]
        at net.minecraft.server.MinecraftServer.doRunTask(MinecraftServer.java:1423) ~[paper-1.18.1.jar:git-Paper-216]
        at net.minecraft.server.MinecraftServer.c(MinecraftServer.java:189) ~[paper-1.18.1.jar:git-Paper-216]
        at net.minecraft.util.thread.BlockableEventLoop.pollTask(BlockableEventLoop.java:122) ~[?:?]
        at net.minecraft.server.MinecraftServer.pollTaskInternal(MinecraftServer.java:1400) ~[paper-1.18.1.jar:git-Paper-216]
        at net.minecraft.server.MinecraftServer.pollTask(MinecraftServer.java:1393) ~[paper-1.18.1.jar:git-Paper-216]
        at net.minecraft.util.thread.BlockableEventLoop.runAllTasks(BlockableEventLoop.java:110) ~[?:?]
        at net.minecraft.server.MinecraftServer.tickServer(MinecraftServer.java:1528) ~[paper-1.18.1.jar:git-Paper-216]
        at net.minecraft.server.MinecraftServer.runServer(MinecraftServer.java:1273) ~[paper-1.18.1.jar:git-Paper-216]
        at net.minecraft.server.MinecraftServer.lambda$spin$0(MinecraftServer.java:317) ~[paper-1.18.1.jar:git-Paper-216]
        at java.lang.Thread.run(Thread.java:833) ~[?:?]