If you’re wondering why Aer Lingus won’t let you check in online, several common reasons could be responsible. Aer Lingus typically allows online check-in starting 48 hours before departure for most flights, closing 2 hours before short-haul flights and 2 to 3 hours before long-haul international flights. However, certain conditions may block online check-in for specific passengers. The most frequent issue is passport or visa verification. If you’re traveling to a country that requires physical verification of travel documents, Aer Lingus will require you to complete check-in at the airport. This ensures that your travel documents, such as visas or passports, meet entry requirements. Another common reason involves codeshare flights. If your booking includes a flight operated by a partner airline (not Aer Lingus), you may be redirected to the other airline’s website or be required to check in manually at the airport. These technical limitations often prevent Aer Lingus from processing your full itinerary online. If you're traveling with special service requests—such as wheelchair assistance, unaccompanied minors, or pets—online check-in is generally disabled. These services require extra steps and verification by staff at the airport, and therefore cannot be completed online. Group bookings, especially those with more than nine passengers, are also not eligible for online check-in and must be completed in person. Inaccurate or incomplete passenger information, such as misspelled names, incorrect passport numbers, or missing contact details, can prevent the system from allowing check-in. If your booking was made through a third-party website, and your personal details weren’t entered correctly, online check-in may be restricted. Always ensure your booking matches your travel documents exactly. Additionally, if there are unpaid fees on your booking—such as extra baggage charges, seat selection costs, or pending itinerary changes—Aer Lingus may prevent online check-in until the balance is cleared. If your flight was changed or rebooked, especially after a cancellation or disruption, the check-in system may not reflect your most recent booking immediately. In such cases, it’s best to use the updated booking reference or wait a few hours before trying again. Occasionally, technical errors with the website or mobile app may also prevent check-in. Browser issues, outdated apps, or poor connectivity can interfere with the process. Try clearing your browser cache, updating the app, or switching devices. Some airports may also have local restrictions that block mobile or online check-in for specific routes, particularly if additional airport security checks are required. In summary, Aer Lingus may not let you check in online due to one or more of the following: travel document checks, codeshare flights, special requests, booking issues, outstanding fees, or technical problems. To avoid delays, confirm your details, check for restrictions, and complete any pending payments. If issues continue, it’s best to arrive early at the airport and use the check-in counter. For further help, contact Aer Lingus customer support directly to clarify the specific reason for your check-in issue.