MacBook Pro Retina Black Screen

Hi,

since the last update of the MacOS I encounter black screens during normal work with the MBP.

The keyboard light is still on, but screen is black. Sometimes he reboots automatically and everything seems to work fine again until the next black screen. sometime I need several tries to restart the MBP manual until he really reboots again,

Anybody an idea what could be the reason?

MBP is approx 4 to 5 years old with current Safaris on it and 256 GB SSD

no external device is connected

Thanks