Include an upload box in a popover

I am working on making a mockup dash where I could upload data in a popover window. My problem (shown in the error) is I do not know how to condition the callback of the upload to the popover being open. Any idea how I could do it?

Cheers

So I have figured out how to solve the problem in the callback of the upload I have added a condition that checks that the the popover is open and an else with :

raise PreventUpdate

so that it does not return none