Holiday shopping started early this year, but shoppers were hit by 2 billion out-of-stock messages in October alone due to the supply chain crisis

• In October, online shoppers saw 2 billion out-of-stock messages - three times more than in October 2019.
• Electronics has the highest out-of-stock levels, following by jewelry, apparel, home and garden, and pet products.

The holiday shopping season is just getting started, but online shoppers are already getting whacked with out-of-stock messages as the supply chain crisis threatens to ruin Christmas.

Last month alone, online shoppers saw 2 billion out-of-stock messages - three times more than in October 2019 -according to an Adobe Analytics study released Tuesday. The analysis covered one trillion visits to US retail sites.

This year, consumers have started shopping ahead of time as they've been enticed by earlier deals, said Adobe. But, "as e-commerce demand picks up, shoppers are feeling the impact of ongoing supply chain constraint," Adobe said in its report.

Some $72.4 billion was spent on US retail sites in October - an 8% growth from a year ago, said Adobe. In the first 10 months of the year, consumers spent $680 billion online - that's a 9% increase from a year ago, and 57% higher than in 2019 before the pandemic, according to Adobe. The spending is driven by purchases of toys, groceries, video games, and gift cards.

Of the 18 product categories covered in Adobe's analysis, electronics has the highest out-of-stock levels, followed by jewelry, apparel, home and garden, and pet products.

Electronic products have been hit by a global chip shortage that has already cost tech giant Apple $6 billion as its production is struggling to catch up with demand. Nintendo has also said it can't fulfill the holiday demand for its Switch gaming consoles due to the chip shortage, Reuters reported.

Retailers and logistics experts are urging people to start shopping early this year to ensure that they get their presents and Christmas trees.

"Some have begun to adjust their holiday strategy accordingly, with parents shopping for toys earlier and some settling for gift cards this season," said Taylor Schreiner, director of Adobe Digital Insights, in the report. "For those who have not yet started their holiday shopping, they will need to be prepared to be flexible."