Hello, I just upgrade my software to 1.4.01 and now my machine never ends a cut as get frozen on M2 command. The progress bar says busy and the timer keeps counting. If I press the stop button manuall

The fastest way is to change whatever strange setting happened is to revert user preferences.
In LightBurn, click File then click Load Prefs Backup and pick a file dated when LightBurn was working well for you.
Click Load.
That should remove any strange settings associated with your recent update.
Your profile says, “Sculpfun S9 Laser with a custom made machine”
is the controller custom or are you using the Sculpfun S9 controller?