The system error, which lasted for at least two hours Thursday night, was triggered by routine maintenance, Webvan spokeswoman Amy Nobile said. Scores of the Web supermarket's customers could navigate the site but were unable to check out or schedule delivery times.
"We still have no idea what time our order will be delivered tomorrow," one customer said in an email to CNET News.com Thursday evening. "They have to call us back in the morning."
The glitch comes a week after Foster City, Calif.-based Webvan unveiled a redesigned Web site. However, Nobile said the face-lift had nothing to do with Thursday's problems.
"The problem has been fixed, and we don't anticipate it affecting systems again," she said.
Whatever the cause, the error came during a crucial time for Webvan. The Thanksgiving shopping season in the United States is the busiest time of year for online and offline grocers. Webvan is also in the middle of a massive effort to turn a profit at its San Francisco Bay Area operations, which would help prove its business model.
Webvan last quarter missed its goal of breaking even in the San Francisco Bay Area. The company has also grappled with delivery issues and diminishing traffic to its site.
Nobile said that the company did not notice any decline in sales for Thursday. The San Francisco Bay Area operation saw sales on par with those of the other nine cities Webvan does business in, including Chicago, Atlanta and Sacramento, Calif.
Meanwhile, other Web grocers have been struggling. This past week, two Massachusetts-based online grocers, Streamline.com and ShopLink.com, said they were ceasing operations.
During the past two holiday seasons, many e-tail sites have buckled under added traffic or have been unable to deliver goods on time. Companies that suffered holiday mishaps included Toysrus.com, Amazon.com and Macys.com.
Analysts have said that for many online stores, the way they perform this holiday season could be the difference between making it to the next one or heading to the dot-com graveyard.