Customer reviews on social media were not kind to Amazon during its Prime Day sale on Tuesday, as the company's second annual sale was marred by issues at the online checkout page.

Amazon has touted its annual Prime Day sale as a members-only, online version of Black Friday, but many Canadian and U.S. customers said they were unable to make any purchases during the much-hyped event. Some said the site was erroneously telling customers that they had already claimed deals before their purchases were complete, while others said they were unable to add items to their online shopping carts.

Several people griped about the problem on social media, using the hashtag #PrimeDayFail.

Amazon said in a tweet that it's "working to resolve" the checkout issue as quickly as possible.

While some items were deeply discounted, many customers had a laugh at some of the minor bargains, tweeting photos of "deals" that offered only a few cents off.

Amazon.ca Prime Day sales are offered exclusively to customers with a Prime membership, which costs $79 a year. However, customers looking to get in on the deals can sign up for a free 30-day trial.