Lot of Warning in behavior Trees

anonymous_user_b1c15813 · January 8, 2015, 9:59pm

Why I am getting this warning in behavior trees?

LogBehaviorTree:Warning: OnCeaseRelevant called on Blueprint service None with invalid owner. OwnerComponent: BTComponent, OwnerComponent Owner: BP_AIVehicleController_C_0. OwnerComponent has BeginDestroyed flag

Thanks,

MieszkoZ · January 9, 2015, 10:31am

Sounds like your BT is being run for AI that has been killed. To avoid it call StopLogic on your AI controller’s BrainComponent.

Cheers,

–mieszko

Justin.Dooley · January 9, 2015, 2:29pm

Just to add on to this, I find it good practice to destroy the controller before the pawn. simply because a pawn can exist for an extra frame without a controller if it’s really required but you can get errors if your controller tries to run logic on your pawn and it does not exist anymore.

anonymous_user_b1c15813 · January 9, 2015, 4:23pm

Mieszko and Justin, thanks for replying.
Now this may be a stupid question but I am not able to find “Brain component” in AIController. Is it only on c++ side now? When I search for brain component in blueprint, only thing its giving me is “Cast to Brain component”.
Please let me know what I am doing wrong here.

Thanks,

MieszkoZ · January 12, 2015, 12:28pm

Maybe it’s not available in the version you’re using?

anonymous_user_b1c15813 · January 12, 2015, 3:14pm

ohhh, is it in 4,7? I am currently using 4.6.1.

Thanks,

MieszkoZ · January 12, 2015, 4:09pm

Yes, it’s available in 4.7.

anonymous_user_b1c15813 · January 12, 2015, 4:16pm

Ok cool. I will then upgrade it to 4,7.

Thanks for help and all the awesome things you guys are doing for UE4.

Thanks,

MieszkoZ · January 12, 2015, 4:17pm

Don’t mention it. Keep on using it!

Slonopotamus · February 26, 2015, 2:53pm

This error message happens during normal destruction of AIController with running BT (for example, when Stop is pressed in editor), so I think it is an engine bug.

Slonopotamus · February 28, 2015, 8:20am

Mieszko, I created a simple project that reproduces this bug. Just open it in editor and press Play/Stop. As you’ll see in comments in BTService.uasset, there are actually two bugs related to NotifyDeactivation:

OnCeaseRelevant isn’t called unless BTService implements NotifyActivation. Why? Maybe I don’t care about activation, I only want deactivation callback.
NotifyDeactivation isn’t called when Stop is pressed.

So, looks like BehaviorTreeComponent::Cleanup isn’t properly doing what it is supposed to do.

Slonopotamus · February 28, 2015, 8:49am

Answering to myself: I think it was fixed by

commit e0acca6e4614bbe4b88ab75da683698497c33987
Author: Lukasz Furman <Lukasz.Furman@epicgames.com>
Date:   Fri Dec 19 05:52:26 2014 -0500

    added OnTaskFinished event to behavior tree task nodes,
    always calling OnCeaseRelevant and OnTaskFinished on active nodes when tree finishes (restart / end play)
    
    [CL 2393632 by Lukasz Furman in Main branch]

Note that this commit wasn’t included in 4.7.