CNN on Friday corrected an erroneous report that Donald Trump Jr. had received advance notice from the anti-secrecy group WikiLeaks about a trove of hacked documents that it planned to release during last year’s presidential campaign.

In fact, the email to Mr. Trump was sent a day after the documents, stolen from the Democratic National Committee, were made available to the general public. The correction undercut the main thrust of CNN’s story, which had been seized on by critics of President Trump as evidence of coordination between WikiLeaks and the Trump campaign.

It was also yet another prominent reporting error at a time when news organizations are confronting a skeptical public, and a president who delights in attacking the media as “fake news.”

Last Saturday, ABC News suspended a star reporter, Brian Ross, after an inaccurate report that Donald Trump had instructed Michael T. Flynn, the former national security adviser, to contact Russian officials during the presidential race.

The report fueled theories about coordination between the Trump campaign and a foreign power, and stocks dropped after the news. In fact, Mr. Trump’s instruction to Mr. Flynn came after he was president-elect.

Several news outlets, including Bloomberg and The Wall Street Journal, also inaccurately reported this week that Deutsche Bank had received a subpoena from the special counsel, Robert S. Mueller III, for President Trump’s financial records.

The president and his circle have not been shy about pointing out the errors.

“I know you can’t help but spread #fakenews @cnn,” Donald Trump Jr. tweeted on Friday. And in the wake of ABC News suspending Mr. Ross, the president celebrated on Twitter, writing, “More Networks and ‘papers’ should do the same with their Fake News!” He also encouraged “People who lost money when the Stock Market went down” to sue ABC for damages.

CNN’s erroneous scoop, about the email to Donald Trump Jr., rocketed around cable news and social media on Friday morning. But it fell apart after The Washington Post reported that the email — which included a decryption key to access hacked documents — was dated Sept. 14, not Sept. 4, as CNN initially reported. WikiLeaks publicized links to the documents in question on Sept. 13.

CNN said that its report had been based on information from two sources and vetted by the network’s in-house fact-checking team. But both sources were apparently incorrect about the date of the message.

“The new information indicates that the communication is less significant than CNN initially reported,” CNN wrote in an updated article.

There were lamentations on social media in the wake of CNN’s error, as some press advocates worried that it could further erode trust in the media and gird the president’s attacks.

“Between this and Brian Ross’ Flynn mistake, the mainstream media is doing a great job of bolstering Trump’s claims about fake news,” wrote James Surowiecki, a former columnist for The New Yorker. “It’s the most obvious thing to say, but reporters need to SLOW DOWN. Being right is more important than being first.”

In June, CNN severed ties with three journalists after a botched report about ties between Russia and a Trump confidant, Anthony Scaramucci, who went on to briefly serve as the White House communications director.

On Friday, the network said it would take no disciplinary action in this latest case, because the reporters, Manu Raju and Jeremy Herb, followed its editorial guidelines. Mr. Raju also appeared on-air on Friday afternoon to correct his prior report.