Engine doesn't start up at the first attempt

[AUDID]

Hi everyone, i have a problem on my a6 tdi ultra business 150hp 2017 .

Sometimes i push the start botton, the MMI screen comes up normally and the display and  radio both work regularly. But the engine doesnt start. It only does after a few attempts.  I am thinkin about a problem on the start and stop botton, or maybe on the break pedale sensor.  Any suggestion? Please let me know.  It happens from time to time, not every day.  Thanks , D.