Here is a list of the call stack every time it does this. It does it pretty much on clock work every month or so when the system fires off to see if any settlements are going to rebel.
at System.ThrowHelper.ThrowKeyNotFoundException()
at System.Collections.Generic.Dictionary`2.get_Item(TKey key)
at TaleWorlds.CampaignSystem.SandBox.CampaignBehaviors.RebellionsCampaignBehavior.GetClanIdForNewRebelClan(CultureObject culture)
at TaleWorlds.CampaignSystem.SandBox.CampaignBehaviors.RebellionsCampaignBehavior.CreateRebelPartyAndClan(Settlement settlement)
at TaleWorlds.CampaignSystem.SandBox.CampaignBehaviors.RebellionsCampaignBehavior.StartRebellionEvent(Settlement settlement)
at TaleWorlds.CampaignSystem.SandBox.CampaignBehaviors.RebellionsCampaignBehavior.DailyTickSettlement(Settlement settlement)
at TaleWorlds.CampaignSystem.MbEvent`1.InvokeList(EventHandlerRec`1 list, T t)
at TaleWorlds.CampaignSystem.CampaignEvents.DailyTickSettlement(Settlement settlement)
at TaleWorlds.CampaignSystem.CampaignEventDispatcher.DailyTickSettlement(Settlement settlement)
at TaleWorlds.CampaignSystem.PeriodicTicker`1.PeriodicTickSome(Single timeUnitsElaped)
at TaleWorlds.CampaignSystem.Campaign.PeriodicDailyTick(Single deltaDays)
at TaleWorlds.CampaignSystem.Campaign.Tick(Single dt)
at TaleWorlds.CampaignSystem.Campaign.RealTick(Single realDt)
at TaleWorlds.CampaignSystem.MapState.OnMapModeTick(Single dt)
at TaleWorlds.Core.GameStateManager.OnTick(Single dt)
at TaleWorlds.Core.Game.OnTick(Single dt)
at TaleWorlds.Core.GameManagerBase.OnTick(Single dt)
at TaleWorlds.MountAndBlade.Module.OnApplicationTick_Patch2(Module this, Single dt)
at System.ThrowHelper.ThrowKeyNotFoundException()
at System.Collections.Generic.Dictionary`2.get_Item(TKey key)
at TaleWorlds.CampaignSystem.SandBox.CampaignBehaviors.RebellionsCampaignBehavior.GetClanIdForNewRebelClan(CultureObject culture)
at TaleWorlds.CampaignSystem.SandBox.CampaignBehaviors.RebellionsCampaignBehavior.CreateRebelPartyAndClan(Settlement settlement)
at TaleWorlds.CampaignSystem.SandBox.CampaignBehaviors.RebellionsCampaignBehavior.StartRebellionEvent(Settlement settlement)
at TaleWorlds.CampaignSystem.SandBox.CampaignBehaviors.RebellionsCampaignBehavior.DailyTickSettlement(Settlement settlement)
at TaleWorlds.CampaignSystem.MbEvent`1.InvokeList(EventHandlerRec`1 list, T t)
at TaleWorlds.CampaignSystem.CampaignEvents.DailyTickSettlement(Settlement settlement)
at TaleWorlds.CampaignSystem.CampaignEventDispatcher.DailyTickSettlement(Settlement settlement)
at TaleWorlds.CampaignSystem.PeriodicTicker`1.PeriodicTickSome(Single timeUnitsElaped)
at TaleWorlds.CampaignSystem.Campaign.PeriodicDailyTick(Single deltaDays)
at TaleWorlds.CampaignSystem.Campaign.Tick(Single dt)
at TaleWorlds.CampaignSystem.Campaign.RealTick(Single realDt)
at TaleWorlds.CampaignSystem.MapState.OnMapModeTick(Single dt)
at TaleWorlds.Core.GameStateManager.OnTick(Single dt)
at TaleWorlds.Core.Game.OnTick(Single dt)
at TaleWorlds.Core.GameManagerBase.OnTick(Single dt)
at TaleWorlds.MountAndBlade.Module.OnApplicationTick_Patch2(Module this, Single dt)

