The Pole qualified last, eight tenths behind his team-mate George Russell.
“I do not know why it is happening again but we have to understand it, because it happens too often,” said Kubica.
“There was no grip, the tyres slid so much at both the front and the rear.
“I’m fighting just to stay on track. It puts me in a difficult situation. When the car starts to slide like that it’s just impossible to drive.
“I don’t think it’s a matter of the setup, because too often things are happening that are difficult to understand,” concluded Kubica.
Source: Eleven Sports