Hi Umberto, you might want to check the Coautl code that fetches the plan from Simbrief and add an exception in the case a file plan doesn't exist.
Coautl kept crashing for me after updating to the latest version using the offline installer, but after enabling the log, I deduced the culprit was that I didn't have a flight plan filed in Simbrief before loading the aircraft (I wasn't logged in at all in Simbrief... I hadn't used the PC for a month or so).
It was an endless loop that kept crashing Coautl without any clue. This is in P3D (v5.3 HF2). So, maybe an exception to avoid the crash might help!
Hope this helps