Thank you for your quick reply and fast fix, but, it did not work. I`ve downloaded the file, extracted it, copy+pasted data folder into my main game folder, overwrote all folders and files when asked, and, tried both of my saves. In both cases it still gives the error message.
Do I need to start a new campaign, or, delete some additional file to make it work? I don`t want to start a new campaign, if not necessary.