Console says waiting for connection / message: There was a problem sending data to the laser. The machine may be busy or paused

When I hit start, Lightburn message says :
There was a problem sending data to the laser.

The machine may be busy or paused.
console says:
Waiting for connection…

Waiting for connection…

File imported in 49 milliseconds

Waiting for connection…

Port failed to open - already in use?

Waiting for connection…

Port failed to open - already in use?

PLEASE HELP!!!
I don’t know how to fix.
Thanks