French phrase
Depuis quand ~ se produit-il ?
Meaning
Since when has ___ been happening?
When to use it
Asks when an event or problem first began. It is a polite, somewhat formal way to ask about an ongoing issue.
Example dialogue
Depuis quand le problème sur le serveur se produit-il ?
Since when has the server problem been happening?
Il a commencé hier matin, nous enquêtons pour trouver la cause.
It started yesterday morning; we're investigating to find the cause.