MONTREAL -- Air Canada says it's "business as usual" now that the airline has completed its migration to a new reservation system, but some social media users complained of system failures.

"We have now migrated to a new reservation system to improve your travel experience," the airline said in a statement on its website posted late Tuesday morning. "It is business as usual and reservation services including flight purchase and booking modification are available."

Air Canada began its migration to the new booking system at 8 p.m. Monday and completed it Tuesday mid-morning. During that time travellers were unable to make or modify reservations online or by phone.

All passenger bookings and personal information remained secure throughout the migration to the new system, the airline announced.

But on Tuesday evening, dozens of people had taken to twitter with messages criticizing the airline's new system. Many said they couldn't buy tickets, or access reservations on the new system.

What the hell happened to my Air Canada app.? It’s beyond useless. @AirCanada — @excovkid (@MartynLengden) November 20, 2019

@AirCanada with your migration to new site, my passenger name has been mangled and is now incorrect, I cannot get into my reservation to update my preference. Your call centre has a message that it has exceeded its capacity and cannot place me hold. Help! My flight is tomorrow. — Denise A Cole (@MissMcFoy) November 20, 2019

A spokesperson for the airline told CTV News late Tuesday that the airline was dealing with problems, but did not specify what those technical issues were.

"We completed the data migration today and are now operating our reservation, ticketing and inventory processes on the new system," a spokesperson said in an emailed statement. They added that the system was encountering difficulties, but did not specify the nature of the problems.

"There are some temporary issues which can arise in any IT project of this magnitude, and we are working hard to identify and resolve these as soon as possible."

It was unclear Tuesday evening why so many people were having trouble with the system.