Hi @Arrm1n
I have some solution for that problem :
Re-Install Truckersmp Launcher
Reboot your computer
Re-install NetFramework
Run as administrator when launching TruckersMP
I hope I was able to answer your question with my answers.
If you have any questions, feel free to ask me.
If this answer solves your problem, you can click "Vote this answer up" which may help other players as well
Kind Regrads,
Linux OS