ConcurrentModificationException

 public String selChar(String character, IUser author, IGuild guild, GuildConfig guildConfig) {
        List<IRole> userRoles = author.getRolesForGuild(guild);
        for (CharacterObject c : characters) {
            if (c.getName().equalsIgnoreCase(character)) {
                int i = 0;
                for (IRole uRole : userRoles) {  // <<------------------ Line Affected
                    for (RoleTypeObject r : guildConfig.getCosmeticRoles()) {
                        if (r.getRoleID().equalsIgnoreCase(uRole.getID())) {
                            userRoles.remove(i);
                        }
                    }
                    i++;
                }
                i = 0;
                for (RoleTypeObject r : c.getRoles()) {
                    if (guild.getRoleByID(r.getRoleID()) != null) {
                        userRoles.add(guild.getRoleByID(r.getRoleID()));
                    } else {
                        c.getRoles().remove(i);
                    }
                    i++;
                }
                Utility.roleManagement(author,guild,userRoles);
                Utility.updateUserNickName(author,guild,c.getNickname());
                return "> Loaded Character.";
            }
        }
        return Constants.ERROR_CHAR_NOT_FOUND;
    }


java.lang.reflect.InvocationTargetException
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at Handlers.MessageHandler.handleCommand(MessageHandler.java:250)
    at Handlers.MessageHandler.<init>(MessageHandler.java:76)
    at Listeners.AnnotationListener.onMessageRecivedEvent(AnnotationListener.java:128)
    at sun.reflect.GeneratedMethodAccessor6.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at sx.blah.discord.api.events.EventDispatcher.lambda$null$11(EventDispatcher.java:323)
    at java.util.concurrent.CopyOnWriteArrayList.forEach(CopyOnWriteArrayList.java:890)
    at sx.blah.discord.api.events.EventDispatcher.lambda$null$12(EventDispatcher.java:321)
    at java.util.concurrent.ConcurrentHashMap.forEach(ConcurrentHashMap.java:1597)
    at sx.blah.discord.api.events.EventDispatcher.lambda$null$13(EventDispatcher.java:320)
    at java.util.stream.ForEachOps$ForEachOp$OfRef.accept(ForEachOps.java:184)
    at java.util.stream.ReferencePipeline$3$1.accept(ReferencePipeline.java:193)
    at java.util.stream.ReferencePipeline$2$1.accept(ReferencePipeline.java:175)
    at java.util.concurrent.ConcurrentHashMap$EntrySpliterator.forEachRemaining(ConcurrentHashMap.java:3606)
    at java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:481)
    at java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:471)
    at java.util.stream.ForEachOps$ForEachOp.evaluateSequential(ForEachOps.java:151)
    at java.util.stream.ForEachOps$ForEachOp$OfRef.evaluateSequential(ForEachOps.java:174)
    at java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234)
    at java.util.stream.ReferencePipeline.forEach(ReferencePipeline.java:418)
    at sx.blah.discord.api.events.EventDispatcher.lambda$dispatch$17(EventDispatcher.java:319)
    at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
    at java.util.concurrent.FutureTask.run(FutureTask.java:266)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    at java.lang.Thread.run(Thread.java:745)
Caused by: java.util.ConcurrentModificationException
    at java.util.ArrayList$Itr.checkForComodification(ArrayList.java:901)
    at java.util.ArrayList$Itr.next(ArrayList.java:851)
    at POGOs.Characters.selChar(Characters.java:58)
    at Handlers.MessageHandler.selChar(MessageHandler.java:978)
    ... 31 more