Well, since then, I lost 2 days of development trying to figure out what is the cause of this annoying following situation.
Well, I set up an external event. Then went to main scene, events tab and linked the external event there.
Press play and GDevelop crashes. Every freaking time.
If I delete my linked external event, press play and the game opens up.
I'm very frustrated cause I do not intend to go back to Windows just to make GDevelop to run properly, I want to use it on Lubuntu. I'll be very relieved if anyone would help me with that. Thanks.