Under the Location option in the top-left Apple menu I have set up a few different options that let me quickly swap between different web proxy configurations when I connect to different networks. Normally I can just choose one and the new settings are applied immediately.
It has started showing this message if I try to choose a different location while Firefox is open.
The location doesn’t change and Firefox doesn’t actually close. I have to press Ignore, close Firefox, change location and re-open Firefox.
What is the cause of this?