Expired or lost passports – France
Whilst you should avoid travelling with expired documents, if you have French nationality and if your trip is for less than 3 months, you may travel on an expired passport to countries that have signed and ratified the European Agreement on Regulations governing the Movement of Persons between Member States of the Council of Europe, as long as the passport has not been expired for more than 5 years. However, you will need to have a valid ID card instead.
If you are a national of another EU country which has signed and ratified the Convention, you may travel to France (for a trip of 3 months or less) as long as you have one of the documents listed under your country in the annex to the Convention.
In a very few situations, French citizens may also ask for an fr on medical or humanitarian grounds or for professional reasons.
The French Foreign Affairs Ministry's website contains useful advice on fr.