I get a full log of errors?

17.12 20:31:37 [Server] INFO ... 15 more
17.12 20:31:37 [Server] INFO at org.bukkit.command.PluginCommand.execute(PluginCommand.java:40)
17.12 20:31:37 [Server] INFO at com.mcbans.firestar.mcbans.BukkitInterface.onCommand(BukkitInterface.java:180)
17.12 20:31:37 [Server] INFO at com.mcbans.firestar.mcbans.commands.CommandHandler.execCommand(CommandHandler.java:126)
17.12 20:31:37 [Server] INFO at java.util.regex.Pattern.matcher(Pattern.java:1088)
17.12 20:31:37 [Server] INFO at java.util.regex.Matcher.(Matcher.java:228)
17.12 20:31:37 [Server] INFO at java.util.regex.Matcher.reset(Matcher.java:308)
17.12 20:31:37 [Server] INFO at java.util.regex.Matcher.getTextLength(Matcher.java:1233)
17.12 20:31:37 [Server] INFO Caused by: java.lang.NullPointerException
17.12 20:31:37 [Server] INFO ... 12 more
17.12 20:31:37 [Server] INFO at org.bukkit.command.PluginCommand.execute(PluginCommand.java:40)
17.12 20:31:37 [Server] INFO at com.earth2me.essentials.Essentials.onCommand(Essentials.java:359)
17.12 20:31:37 [Server] INFO at com.earth2me.essentials.Essentials.onCommandEssentials(Essentials.java:389)
17.12 20:31:37 [Server] INFO at org.bukkit.command.PluginCommand.execute(PluginCommand.java:42)
17.12 20:31:37 [Server] INFO Caused by: org.bukkit.command.CommandException: Unhandled exception executing command 'ban' in plugin mcbans v3.6
17.12 20:31:37 [Server] INFO at net.minecraft.server.ThreadServerApplication.run(SourceFile:457)
17.12 20:31:37 [Server] INFO at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:425)
17.12 20:31:37 [Server] INFO at net.minecraft.server.MinecraftServer.w(MinecraftServer.java:527)
17.12 20:31:37 [Server] INFO at net.minecraft.server.NetworkListenThread.a(SourceFile:108)
17.12 20:31:37 [Server] INFO at net.minecraft.server.NetServerHandler.a(NetServerHandler.java:93)
17.12 20:31:37 [Server] INFO at net.minecraft.server.NetworkManager.b(NetworkManager.java:226)
17.12 20:31:37 [Server] INFO at net.minecraft.server.Packet3Chat.a(Packet3Chat.java:33)
17.12 20:31:37 [Server] INFO at net.minecraft.server.NetServerHandler.a(NetServerHandler.java:715)
17.12 20:31:37 [Server] INFO at net.minecraft.server.NetServerHandler.chat(NetServerHandler.java:722)
17.12 20:31:37 [Server] INFO at net.minecraft.server.NetServerHandler.handleCommand(NetServerHandler.java:757)
17.12 20:31:37 [Server] INFO at org.bukkit.craftbukkit.CraftServer.dispatchCommand(CraftServer.java:378)
17.12 20:31:37 [Server] INFO at org.bukkit.command.SimpleCommandMap.dispatch(SimpleCommandMap.java:165)
17.12 20:31:37 [Server] INFO at org.bukkit.command.PluginCommand.execute(PluginCommand.java:42)
17.12 20:31:37 [Server] INFO org.bukkit.command.CommandException: Unhandled exception executing command 'ban' in plugin Essentials v2.6.5
17.12 20:31:37 [Server] SEVERE null

Could you verify which version of MCBans you are using please?
Essentials appears to be trying to handle the command too.