Amazon's self-created Prime Day holiday got off to a rocky start.

The retailing giant's website experienced periodic outages on desktop and mobile on Monday afternoon, right after the Prime Day sale began at 3 p.m. ET. Many shoppers hoping to score deals were instead met with photos of cute dogs, the company's standard error page.

That put Amazon in the doghouse with upset customers, many of whom have gone on social media to complain.

The issues appeared to affect other Amazon products and services. According to Downdetector.com, a website that tracks outages, Amazon's Alexa, Prime Video Services, and Amazon Web Services experienced brief issues. The AWS issues were limited to management consoles and weren't responsible for the Amazon Prime issues, according to a spokesperson.

Related: Why Prime Day is important to Amazon

In a statement to CNNMoney, Amazon said, "Some customers are having difficulty shopping, and we're working to resolve this issue quickly. Many are shopping successfully -- in the first hour of Prime Day in the U.S., customers have ordered more items compared to the first hour last year. There are hundreds of thousands of deals to come and more than 34 hours to shop Prime Day."

Related: Bezos worth $150 billion as Amazon hits all-time high on Prime Day

Calls to Amazon's customer service number were answered with an automated message saying, "We've heard some customers are having trouble with our website right now. We're very sorry and we expect to have the website fully functioning again soon."

Amazon Prime Day is the company's annual sales bonanza. Lasting for 36 hours this year, it offers discounts on products to Prime Members. It's predicted to reach $3.4 billion in sales this year, according to retail think tank Coresight Research -- that is, if enough people can manage to make their purchases.

In addition to the revenue made on the day itself, it's a marketing opportunity for Amazon, which is always trying to sign up new Prime Members.

"The worst part about it is it's just embarrassing. They're supposed to be the best company in the world from a retail and e-commerce standpoint," said Sucharita Kodali, an ecommerce analyst at Forrester. "This just shows they're human."