The problem, which started on Tuesday, was caused by a new Facebook policy that prohibits new political ads starting a week before the election. After implementing the policy, the company’s automated systems mistakenly blocked some preapproved ads.

Facebook said the problem affected both political campaigns. 

Biden’s campaign said thousands of its ads have been blocked and remain so. The mishap, the campaign added, has caused it to miss out on reaching a huge number of voters and $500,000 in fundraising.

Compounding the problem, Biden’s campaign said, is that Facebook has failed to provide details about the “widespread issues.”

“We have no scale of the problem, who it is affecting, and their plan to resolve it,” Rob Flaherty, digital director for the Biden campaign, said in a statement. “We find ourselves five days out from Election Day unable to trust that our ads will run properly, or if our opponents are being given unfair, partisan advantage.”

Facebook blamed the issue on a technical glitch as well as confusion from advertisers, including the presidential campaigns, about what is permitted and when.

In addition to the ad problem, Biden’s campaign has criticized Facebook for doing little to police misinformation on its service. Then last month, the campaign condemned the company for failing to protect the election by allowing misinformation about voting to remain on its network.

The campaign said it’s been working with Facebook “in good faith” to understand the company’s shifting policies and to push for equal enforcement of its rules. But the latest snafu shows that “just five days before Election Day, they have failed to meet the moment,” said Flaherty. 

“It is abundantly clear that Facebook was wholly unprepared to handle this election despite having years to prepare,” he said.

Facebook said “most” issues have been fully addressed, and that it’s working with advertisers to handle their concerns. The company also stressed that no ads were paused or rejected by humans or based on partisan ideologies. 

“We have worked throughout this election to maintain a neutral playing field, and that remains true in the face of these problems,” Facebook said in a blog post. “We understand that time is of the essence at this stage of the campaign season.”