Running the latest release (1.3.5) on Ubuntu 20.04.1 LTS, 16gB of RAM, Nvidia GeForce GT 740 video card with 4gB of VRAM (driver 450.80.02), in windowed mode on a standard 1080P display.
Launching the Avorion app via Steam opens the splash screen, followed by the main menu (with proper background and rotating ship model.) Selecting any game (single/multi) and starting all works fine. Selecting a game mode and starting, the display switches to Loading OK. But once the sector loads and you hit spacebar, the entire graphics stack crashes to a black screen with Ubuntu boot logo, and the machine needs to be rebooted in order to reset the graphics card, etc.
This happens independently of the game mode, server, mods, etc. on a stock, vanilla install of Avorion. FWIW, all the other Steam games in my account run fine on this Linux box, so I don't believe it's something specific to the particular hardware/software I'm running. Avorion is doing something when switching into the "first person" sector view that is fatal to this hardware/software combination that nothing else on that machine is able to duplicate. It happens every time the game switches into the sector.