What do a day-care center, a vegetarian restaurant, a hair salon, an outdoor clothing maker and an investigative news publisher have in common?

To Facebook, they looked suspiciously like political activists.

Facing a torrent of criticism over its failure to prevent foreign interference during the 2016 election, the giant social network recently adopted new rules to make its advertising service harder to exploit.

Under the new rules, advertisers who want to buy political ads in the United States must first prove that they live in the country and mark their ads with a "paid for by" disclaimer. Any ad Facebook deems to contain political content is stored in a searchable public database.

The new rules are meant to illuminate the sometimes shadowy world of politics on social media and help prevent fraud and abuse by organizations like Russia's Internet Research Agency. But many advertisers, including small businesses and news organizations, are complaining that Facebook's detection system has mistakenly miscategorized their ads as political. All ads that have political content — including the miscategorized ones and ads that are taken down after running — are included in the public database.

Michelle Benson, who runs a children's day-care center in Shirley, N.Y., tried to spend $100 to circulate an ad on Wednesday. The ad said that she had openings for more children this summer. "I will beat anyone's rates and accommodate parents according to their schedule," it read.

The ad contained no reference to any political candidate or issue. But Benson received a notification from Facebook that her ad had been rejected because she was not "authorized to run ads with political content."

A similar thing happened to Jamila Zaidi, who manages a hair salon in Frederick, Md. Zaidi was surprised when her Facebook ad for a store special — "$100 for a full highlight or color service for all new clients!" — was deemed an unlabeled political ad.

The Wild Cow, a vegetarian restaurant in Nashville, felt the effects of the new policy as well when Facebook took down an ad for a fundraising show the restaurant was hosting for a local dog-rescue group. The ad included information about the show along with a photo of a handsome pit bull.

"I was wondering why that didn't get approved," Melanie Cochran, the Wild Cow's co-owner, said when a reporter told her that the ad had appeared in Facebook's political ad archive. "I assumed it had to do with the picture."

Rob Leathern, Facebook's director of product management, said that in all three of these cases, the company's review process had simply not worked as intended.

"These ads were mistakenly marked as political, and those decisions have been overturned," Leathern said. "These are new policies, and it's not going to be perfect at the start. … We think it's better than doing nothing at all."

Facebook has said it is trying to safeguard elections around the world while not disturbing its hugely profitable advertising business, which generated $40 billion in revenue last year.

Facebook's new review system uses a combination of artificial intelligence and human reviewers to determine if an ad is political in nature. Ads flagged as political are kept offline until the advertiser goes through the verification process, which can take several days. It requires the advertiser to submit a photo identification, the last four digits of his or her Social Security number, and a code that is sent in the mail.

"We believe that these tools, which make our mistakes very visible, are working," Leathern said.

Facebook's advertising business is still largely automated. But after the 2016 election, the company pledged to more carefully monitor the ads in its system. It has hired additional moderators to manually screen political ads and is devoting so many resources to the effort that Mark Zuckerberg, Facebook's chief executive, has said that he expects to lose money on political advertising during this campaign cycle.

But the social network's new system also appears to be allowing clearly partisan content to slip through. In a Democratic primary race this month in California's Fourth Congressional District, Facebook allowed a progressive advocacy group, Sierra Nevada Revolution, to run negative ads against one candidate, Regina Bateson. Despite their endorsement of Bateson's rival, the ads were not flagged as political.

Some advertisers are being more patient, perhaps seeing a glitchy advertising filter as better than none at all.

Patagonia, the outdoor clothing company, has seen several of its Facebook ads rejected for mysterious reasons. Still, Scott Carrington, Patagonia's digital and social media marketing manager, seemed to forgive the mistakes.

"While Facebook has more work to do to improve transparency among its users and advertisers, we applaud the steps the company is taking to prevent Russian bots from running and ruining our democracy," Carrington said.