Errors at Gramps Start-up

Try deleting the lifelinechartview_warn.ini in your user plugin directory. Instead of the Win10 locations I detail in the post below here is the Gramps 5.1 Wiki Manual - User Directory. Not a Linux user so not sure if this will work for you.

Here is the wiki for the addon. It may tell you more about the prerequisites.

https://gramps-project.org/wiki/index.php/Life_Line_Chart_View