You cannot check in online if: - Your trip includes travel by train (except from Strasbourg or Brussels). - You used Flying Blue Miles online to obtain an upgrade. - You are traveling with an animal in the hold. There are several reasons why you might not be able to check in online with Air France: Travel Document Verification: If your destination requires a visa, passport check, or health document verification, online check-in may be blocked until these are reviewed at the airport. Special Service Requests: If you’ve requested special assistance (e.g., wheelchair service, unaccompanied minor travel, or traveling with pets), online check-in may not be available, and you must check in at the airport. Code-share Flights: If your flight is operated by another airline (e.g., a partner like Delta or KLM), online check-in may need to be completed on the partner airline’s website instead of Air France. Payment Issues or Unconfirmed Bookings: If your booking hasn’t been fully confirmed or if there are payment irregularities, you won’t be able to check in online. Group Bookings: Online check-in might be restricted for large group reservations. These often require coordination and finalization at the airport. First-Time Travelers or Specific Routes: On certain routes or for first-time flyers, Air France may require in-person verification. Airport Restrictions: Some departure airports may not support online or mobile check-in, especially in certain countries with stricter aviation or immigration procedures. If you're unable to check in online, Air France usually recommends arriving early at the airport and completing check-in at the counter. For specific assistance, contacting their customer service is also a helpful next step.