Is the electronic check-in information valid when the plane is late?

No, the electronic check-in information of the late flight is invalid. Because the flight time will not be adjusted during the flight time, the deadline will not be extended. So the electronic check-in information of the plane is invalid. Electronic boarding pass, also known as "mobile electronic boarding pass", is multimedia information obtained by passengers through online check-in and SMS check-in, including two-dimensional barcode and passenger's name, flight number, boarding gate and seat number.