1.6 Update Error: [Severe] End of Stream (Some Random Ip)

So I just updated to 1.6 and I look at my console and an error keeps appearing: [Severe] End of Stream (some random ip). My server has been running for a long time, a couple months now and this has never happened. Everything seems to be working fine too, I can join, and the plugins seemed to be working. I updated most of my plugins and the error is still occurring.
Plugins:
WorldBorder 1.6.0AutoMessage 2.2.1GroupManager 2.0 (2.10.1) (Phoenix)WorldEdit 5.5.6NoCheatPlus 3.9.2-RC-b520HugsandSlaps 1.3.2BattleTracker 2.5.2.7CreativeGates 1.3.5Permissions 3.1.6Vault 1.2.22-b277HealthBar 1.4.1PlayerHeads 3.0.0088MobArena 0.94.4.98WorldGuard 5.7.5PingMOTD 0.8Essentials Pre2.11.1.6EssentialsProtect Pre2.11.1.6EssentialsSpawn Pre2.11.1.6WhatIsIt 1.3.5ChestShop 3.5EssentialsChat Pre2.11.1.6EssentialsAntiBuild Pre2.11.1.6Factions 1.6.9.4floAuction 2.8.8BattleArena 3.8.8.1.6ArenaPaintball 1.1.0ArenaCTF 1.2.6ArenaSpleef 1.3.6

 

This is a bug of the early build, everyone has this.
It happens when someone with the old launcher tries to connect to your server, tell them to update to 1.6.1 and everything should be fine.

 

Really? Can it effect any sort of resource? Cause lag?

 

navbarry
No. It shouldn't affect your server at all.

 

I don't think It's people trying to join unless about 10 people are trying to join my server every minute of every day....

 

its not outdated client connecting error, it seems to be coming random from players who had been on the server, or are connecting to it, got it on a test server after disconnecting from it.