1, the flight is closed for check-in: Some airlines may open the check-in time in advance or later, please specify the specific time when purchasing tickets. If you can't check in within the specified time, you need to check in at the airport counter or self-service check-in equipment or wait for the next check-in opening time.
2. Incomplete or incorrect booking information: If the information you filled in when purchasing tickets is incorrect or incomplete, such as misspelling, name inconsistent with boarding pass, etc. , you may not be able to complete check-in or even be allowed to board the plane.
3. Policy restrictions: According to the regulations of airlines and the Civil Aviation Administration, some passengers may be subject to some policy restrictions. For example, minors under the age of 18 need to provide guardian's consent, and passengers who have traveled in epidemic areas in the past 14 days need to provide health certificates.
4. Other reasons: If your ticket is cancelled or changed, or your flight has exceeded the check-in deadline, you may not be able to complete check-in. At this point, you can contact the airline or airport customer service to consult the solution.