Overstaying a France Visit Visa is a violation of Schengen rules and can result in serious consequences. These may include fines, being placed on an alert list, refusal of entry in the future, or even a multi-year Schengen ban. If you anticipate needing more time in France due to an emergency, contact the local immigration office (préfecture) immediately. It's always safer to exit the Schengen Area before your permitted days expire.