Why you need insurance when you rent in France
If anything happens to you, or you cause damage at the house you have rented, you are not covered by the home-owner's insurance. This can range from breaking a coffee-table to accidentally burning the house down.
It is a normal condition of renting in France that you have third party/personal liability insurance to cover these sorts of eventualities. This may also be referred to by its French name, assurance villegiature.
The owner's insurance covers eventualities like damage caused by river flooding or faulty wiring, but not any accidental damage caused by you as a renter.
If you are a French resident, no problem, your home insurance covers you when you rent in France. But if you are not French-resident you need adequate personal liability insurance to rent a house. The rental contract you sign will ask for this.
In addition, this type of insurance will also cover you for trip cancellation or interruption.
You may have this insurance as part of your existing travel insurance - if so it is probably referred to as personal liability insurance. If not, you need to take out this insurance within 10 days of booking a rental. You can do this online here.