Auth Session Invalid

[xfury]

The bot runs find for a while the time varies it could be a few min for a few hrs but eventually the bot stops and says Bot Stopped! Reason: Auth Session is invalid. Any ideas whats happening here? Since the log file is too big to upload here is the part where things go screwy.
22:16:03.339 N] [Singular] Casting Hunter's Mark on Ancient Mogu Spirit
[22:16:03.339 D] [Cast] Hunter's Mark 1130
[22:16:03.340 D] [CGSpellBook::CastSpell] Override ID: 1130, KnownIndex: 58
[22:16:03.407 D] [LuaEvents] Getting argument values for event COMBAT_LOG_EVENT_UNFILTERED
[22:16:04.781 D] Stop called!
[22:16:04.781 Q] Bot Stopped! Reason: Auth Session is invalid
[22:16:04.796 D] Activity: Honorbuddy Stopped
[22:16:05.299 D] System.ApplicationException: Cannot run Tick before running Start first!
at Styx.TreeSharp.Composite.Tick(Object context)
at Styx.CommonBot.TreeRoot.()
[22:16:05.299 D] System.ApplicationException: Cannot run Tick before running Start first!
at Styx.TreeSharp.Composite.Tick(Object context)
at Styx.CommonBot.TreeRoot.()
[22:16:05.300 D] Cleared POI - Reason Exception in Root.Tick()
[22:16:05.300 D] Cleared POI
[22:16:05.796 N] Session is invalid!