Not running any other mods - base version: 0.17.43
Max rate version: 3.2.30

Error while running event MaxRateCalculator::on_player_selected_area (ID 49)
Unknown position: screen
stack traceback:
MaxRateCalculator/control.lua:138: in function 'get_gui_root'
MaxRateCalculator/control.lua:517: in function 'open_gui'
MaxRateCalculator/control.lua:988: in function <MaxRateCalculator/control.lua:903>
stack traceback:
[C]: in function 'index'
__MaxRateCalculator/control.lua:138: in function 'get_gui_root'
MaxRateCalculator/control.lua:517: in function 'open_gui'
MaxRateCalculator/control.lua:988: in function <MaxRateCalculator/control.lua:903>

I’m having trouble reproducing this. What was the situation? Was this a recent game save file? Was it the first time you used it in that particular save?

It turns out it's the version of Factorio you're running. My bad, I should have put the correct version dependency into the mod - it should be 0.17.59 or later.

Could you update to the latest version and try again?

Will do - thanks!