Hi, do you observe this behaviour in one of the Vuforia samples ? or is it your own application?

Could you also provide a bit more details on the scenario that (sometimes) triggers this error (like if you launch other activities, etc); that would help!

I tryed to gather some more information on when it happens.

I'm using my own application which is like MainActivity->ImageTargets

from ImageTargets you can press the back key to get back to MainActivity

i noticed it happen only when i quickly close ImageTargets -> get back to main activity -> and very fast go again to ImageTargets..

if i do it slowly it does not happen

any ideas ?

I looks like due to the fast switch back and forth, the second time you try to initialize QCAR while a previous deinitialization has not yet completed.

So, the speed of the activity switch looks like the cause of the issue; maybe put some Logging in your code at various phases of init and deinit (including onPause, onResume, onCreate, onDestroy of ImageTargets), to see if you can get more details on what is precisely  happening

yes, that what i thought.

will try to do it.

seems like the most dirty but simple solution is to just make a 1-2 second timer when resuming the MainActivity

if user will try to move again to ImageTargets and the timer didn't finish the task will just wait for the timer

OK, feel free to share your solution then, might be helpful to others as well.