It was designed to fight misinformation, but a relatively new fact-checking feature on YouTube sputtered on Monday as it displayed information about the Sept. 11 attacks alongside live streams of the fire that ravaged Notre-Dame cathedral.

The mistake, attributed to a misguided algorithm, underscored the difficulties the sprawling video platform faces as it responds to criticism that it has allowed harmful, hateful and false content to flourish virtually unimpeded.

On Monday, news organizations were quick to share live footage on YouTube of the fire as it ripped through Notre-Dame, deeply scarring one of the most recognizable landmarks in Paris. But some of those feeds were presented atop a gray box that, to some viewer confusion, presented information from the Encyclopaedia Britannica about the 2001 terrorist attacks.