A group of Facebook engineers identified a “massive ranking
failure” that exposed as much as half of all News Feed views to
“integrity risks” over the past six months, according to an
internal report on the incident obtained by The Verge.
The engineers first noticed the issue last October, when a sudden
surge of misinformation began flowing through the News Feed, notes
the report, which was shared inside the company last week. Instead
of suppressing dubious posts reviewed by the company’s network of
outside fact-checkers, the News Feed was instead giving the posts
distribution, spiking views by as much as 30 percent globally.
Unable to find the root cause, the engineers watched the surge
subside a few weeks later and then flare up repeatedly until the
ranking issue was fixed on March 11th.
It really does sound like a bug, and some bugs really are devilishly tricky to track down and fix. But it seems a bit odd that it took Facebook six months to fix this one, given how intense the scrutiny of the company has gotten for the very problem this bug made worse.