Solved

Cannot make setup because driver says the car is in a bad way, although it's fully repaired(Sold driver shown in the car/repair)

I cannot change car setup, because the driver says the car is in a bad way, although it's fully repaired. Then I realised, that at the car/repair section my car 2 driver is my previous driver, Adam Johnson, but he's already sold after the last race, and replaced by Daniel Wilson. I guess the main reason of the problem is this.

Bro you can, Just press on try setup then this warning will go away..

When you will click on the Try Setup then this warning will not appear.

You can go to the Drivers & Staff page, re-select your current drivers to be active again, then the error should disappear.