Solved

can't do setup for new driver

about to do 1st race of the season with new 2nd driver. on the setup page driver complain "the car is a bad way..." (the car is obviously fully serviced as it is 1st race of the season). when i proceed with trying a setup, there's an error message pop-up "Oops! there has been an error. please try again."
tried everything from retrying, force close the app and restart, try on different gadget and browser to no avail.

any idea/solution for this?

Have you selected your second driver in the driver tab?
If he isn't assigned it may look like he is able to drive, but he won't be driving.

problem solved!! thanks a million.
but now apparently the practice result swapped between the 2 drivers :) the new driver cannot do practice because all the run of the 1st driver appears on him. but that less of an issue.

thanks again

You can move the drivers around by choosing to set only the driver you want on the left as active (as long as you don't have more than 3 drivers).