Sometimes when bot is running, I noticed that error screenshots as blank or black screen.Why?

Display adapter driver update issues, or issues with recent updates or installations.

multiple reasons - process lag, application lag, internet speed, application up / down, bot not scheduled properly etc.

It's happened a few times with our bots as well. Usually it happens for us when the network goes down or the connection from the control room to the client is lost which is what caused the error to begin with.

I agree that it is possibly a timing issue. you may need to insert a small delay at the top of your error handling task, maybe specific to the page(s)/window(s) the blank screen shots occur at. Can you inject an error at those blank screen shot points to test out the timing?

maybe internet slow. when the screen flickering the white screen appears, on that time screenshot will be taken